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Journal articles on the topic 'Fracture toughness; Mechanical properties'

Author: Grafiati

Published: 4 June 2021

Last updated: 15 February 2022

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Murphy, B. R., and T. H. Courtney. "Mechanochemically synthesized NbC cermets: Part II. Mechanical properties." Journal of Materials Research 14, no. 11 (1999): 4285–90. http://dx.doi.org/10.1557/jmr.1999.0580.

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The mechanical behavior of mechanochemically synthesized NbC cermets was investigated. Material hardnesses range from a high of 19.6 GPa for as-synthesized cermets containing about 4 vol% of Fe to a low of about 4 GPa for heat-treated cermets containing about 34 vol% Cu. Higher hardness generally correlates with lower fracture toughness (about 2 MPa m1/2 for cermets containing the highest percentage of NbC) and vice versa. Highest fracture toughness (about 7.5 MPa m1/2) is found in NbC–18 vol% Fe cermets heat treated extensively following consolidation. Abnormally low fracture toughnesses are found in high-Cu-content cermets in which Cu segregation takes place during heat treatment. Current models of ceramic toughening can be applied to describe the fracture behavior of NbC–Fe cermets.

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Biswas, Nilormi, Arjun Dey, Saugata Kundu, Himel Chakraborty, and Anoop K. Mukhopadhyay. "Mechanical Properties of Enamel Nanocomposite." ISRN Biomaterials 2013 (April 9, 2013): 1–15. http://dx.doi.org/10.5402/2013/253761.

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For adult Indian premolar teeth, we report for the first time ever the simultaneous evaluations of nanohardness, Young's modulus, and fracture toughness of the enamel nanocomposite. The nanohardness and Young's moduli were evaluated from near the beginning of the middle enamel region to within ~10 μm of the dentino-enamel junction (DEJ) and in the dentin region using the nanoindentation technique. The fracture toughness from near the middle of the enamel region to near the DEJ zone was measured using the microindentation technique. The deformation was studied using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM). The relative differences in the extents of biomineralization in the enamel and dentin regions were studied by the energy dispersive X-ray (EDS) technique. The variations of the toughness of the enamel as a function of the toughness of the protein matrix phase have been analyzed which showed that the predicted value of the toughness of the protein present in the nanocomposite was comparable to that of other bioproteins reported in the literature. Further, the work of fracture estimated from the measured value of toughness of the enamel nanocomposite agreed well with the experimental data reported in the literature.

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Low, It Meng, Z. Y. Che, Bruno A. Latella, and K. S. Sim. "Mechanical and Fracture Properties of Bamboo." Key Engineering Materials 312 (June 2006): 15–20. http://dx.doi.org/10.4028/www.scientific.net/kem.312.15.

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The microstructure, mechanical, impact and fracture properties of Australian bamboo have been investigated. The graded composition and property has been confirmed by depth-profiles obtained by synchrotron radiation diffraction and Vickers indentation. The mechanical performance of bamboo is stronly dependent on age. Results showed that young bamboo has higher strength, elastic stiffness and fracture toughness than its old counterpart. Both crack-deflection and crackbridging are the major energy dissipative processes for imparting a high toughness in bamboo.

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Min, Guang Hui, Li Xia Yang, Hua Shun Yu, and Jiande Han. "Mechanical Properties of CaB₆ Sintered Body." Key Engineering Materials 297-300 (November 2005): 2707–12. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.2707.

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In this paper, CaB6 sintered body was fabricated by hot-pressed sintering with/without nickel as a sintering aid. The microstructure and fracture morphology were observed by means of SEM. CaB6 polycrystalline hot-pressed at 2123K showed insufficient densification. Fracture surface revealed that the existence of pores and the poor grain boundaries made the occurrence of intergranular fracture. When 28wt% nickel was added, nearly full density was obtained, although the sintering temperature is 200K lower. Hardness, Bending strength and fracture toughness of polycrystalline CaB6 were measured. By adding the Ni in CaB6 matrix, the flexural strength and the fracture toughness were enhanced, and the ratio of transgranular to intergranular fracture type was increased notably. The fracture surface showed a transgranular fracture. The crack bridging, micro-cracking and crack deflecting were deemed as the contribution to the improved fracture toughness.

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Zhao, Jing Song, Yi Feng, Nan Nan Chen, et al. "Fabrication and Mechanical Properties of Alumina—CNTs Composites." Applied Mechanics and Materials 66-68 (July 2011): 1390–96. http://dx.doi.org/10.4028/www.scientific.net/amm.66-68.1390.

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The transmutation target of nuclear waste material has been fabrication by a powder metallurgy method by using Alumina as the matrix and CNTs as reinforcement. The effect of different nanotube contents on the fracture toughness and the bending strength was investigation. The results showed the fracture toughness and the bending strength of composites increased with increasing CNTs mass fraction when the content of CNTs was less than 1.5%. However, when the contents of CNTs greater than 1.5%, the fracture toughness and the bending strength of composites decreased as the content of CNTs increased. Possible mechanisms are discussed in detail in the paper.

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Zhang, Tao, Hai Yun Jin, Yong Ian Wang, and Zhi Hao Jin. "The Mechanical Properties of AlN/BN Laminated Ceramic Composites." Materials Science Forum 569 (January 2008): 97–100. http://dx.doi.org/10.4028/www.scientific.net/msf.569.97.

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AlN/BN laminated ceramic composites were fabricated using tape-casting and hot-pressing by optimizing the designs of the structure and geometry of AlN/BN laminated ceramic composites. The results showed that the fracture toughness and bending strength for AlN/BN laminated ceramics reached 9.1MPa.m1/2 and 378MPa respectively. The fracture toughness is two times higher than that of AlN monolithic ceramics. The excellent fracture toughness of AlN/BN laminated ceramics could be mainly attributed to crack deflection, delaminating, branching, parallel propagation and crack laminate pilling out at the AlN/BN weak interface.

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Yuan, Zhi Shan, Zheng Lu, You Hua Xie, Xiu Liang Wu, Sheng Long Dai, and Chang Sheng Liu. "Mechanical Properties of a Novel High-Strength Aluminum-Lithium Alloy." Materials Science Forum 689 (June 2011): 385–89. http://dx.doi.org/10.4028/www.scientific.net/msf.689.385.

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As a heat treatable aluminum alloy to be used in T6 and T8 temper, belongs to Al-Cu-Li system, a novel high-strength aluminum-lithium alloy 2A97 was developed. In order to improve the relationships of strength and ductility and fracture toughness, and to urge the applications in the aeronautical and aerospace industries, the effects of normal heat treatments and thermomechanical heat treatments on the mechanical properties and fracture toughness were investigated by Transmission Electron Microscope(TEM), Scanning Electronic Microscope (SEM), tensile test, and fracture toughness test. The results show that for the alloy aged at 135 °C for 24 h after quenching and 4 percent plastic deformation, its microstructures are strengthened by strain hardening and precipitation hardening, consisting of fine T1phase, θ″/θ′ phase and δ′ phase densely and homogeneously distributed in the matrix. It yields optimum relationship of strength and ductility, fracture toughness, its σ0.2, σband δ5are 454 MPa, 536 MPa, and 11.8%, respectively. It yields 43.5 MPa·m1/2of Kqvalues higher than that of 42.5 MPa·m1/2 in T6 temper. The fracture morphologies of impact tensile samples of fracture toughness test and normal tensile test were observed, indicating the dominance of intergranular failure and subintergranular failure with some dimples and trangranular failure.

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Wang, Zhi, Jiajia Zhou, and Long Li. "Fracture Mechanical Properties of Rocklike Materials Under Half Symmetric Loading." Archives of Civil Engineering 63, no. 4 (2017): 71–82. http://dx.doi.org/10.1515/ace-2017-0041.

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AbstractThe authors studied the fracture mechanical properties under half-symmetric loading in this paper. The stress distribution around the crack tip and the stress intensity factor of three kinds of notched specimens under half symmetric loading were compared. The maximum tensile stress σmax of double notch specimens was much greater than that of single notch specimens and the maximum shear stress τmax was almost equal, which means that the single notch specimens were more prone to Mode II fractures. The intensity factors KII of central notch specimens were very small compared with other specimens and they induced Mode I fractures. For both double notch and single notch specimens, KII was kept at a constant level and did not change with the change of a/h, and KII was much larger than KI. KII has the potential to reach its fracture toughness KIIC before KI and Mode II fractures occurred. Rock-like materials were introduced to produce single notch specimens. Test results show that the crack had been initiated at the crack tip and propagated along the original notch face, and a Mode II fracture occurred. There was no relationship between the peak load and the original notch length. The average value of KIIC was about 0.602 MPa×m1/2, and KIIC was about 3.8 times KIC. The half symmetric loading test of single notch specimens was one of the most effective methods to obtain a true Mode II fracture and determine Mode fracture toughness.

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Liu, Xue Quan, Cun Guang Ding, Chang Hai Li, Yi Li, Li Xin Li, and Jin Pu Li. "Microstructure and Mechanical Properties of Sintered Fibrous Monolith Cemented Carbide." Advanced Materials Research 815 (October 2013): 233–39. http://dx.doi.org/10.4028/www.scientific.net/amr.815.233.

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A fibrous monolith cemented carbide with WC-6Co as cell and WC-20Co as cell boundaries was produced through hot co-extrusion process in this paper. The density, hardness, bending strength and fracture toughness of the fibrous monolith cemented carbide were tested, and the fracture and crack propagation were observed by metalloscope and SEM. The results showed that the bending strength and fracture toughness of the fibrous monolith cemented carbides was remarkably improved 71.91% and 45.7% respectively, while the hardness was slightly decreased 1% compared with WC-6Co composites. It is the reason that the tougher shell WC-20Co with higher bending strength and fracture toughness can absorb more fracture energy, which can slow down and prevent the crack propagating from brittle core WC-6Co.

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Sung, Rak Joo, Takafumi Kusunose, Tadachika Nakayama, et al. "Mechanical Properties of Transparent Polycrystalline Silicon Nitride." Key Engineering Materials 317-318 (August 2006): 305–8. http://dx.doi.org/10.4028/www.scientific.net/kem.317-318.305.

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A novel transparent polycrystalline silicon nitride was fabricated by hot-press sintering with MgO and AlN as additives. The mixed powder with 3 wt.% MgO and 9 wt.% AlN was sintered at 1900oC for 1 hour under 30 MPa pressure in a nitrogen gas atmosphere. Transparent polycrystalline silicon nitride was successfully fabricated. The mechanical properties such as density, hardness, young’s modulus, fracture strength and fracture toughness were evaluated. The effect of α/β phase on the mechanical properties of transparent polycrystalline silicon nitride was investigated. The properties were changed depending on the amount of α/β phase. The hardness and Young's modulus increased with increasing the volume fraction of α-phase fraction as a reflection of the higher hardness of α-phase Si3N4. The fracture toughness and fracture strength decreased with decreasing the volume fraction of β-phase Si3N4.

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Peng, Ke Wu, Nian Wen Pu, He Li Ma, Ren Chen, and Yan Wang. "Mechanical Properties and Microstructure of Boron Carbide-Cerium Boride Composite." Advanced Materials Research 482-484 (February 2012): 1551–55. http://dx.doi.org/10.4028/www.scientific.net/amr.482-484.1551.

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The mechanical properties of B4C-CeB6 composite prepared by hot pressed sintering method were tested. The study shows: the hardness of B4C-CeB6 composite increases with the content of cerium boride. When the content of the cerium boride is 4wt%, the hardness reaches its supreme value of 31.98Gpa，its hardness is improved nearly 21.09% compared to monolithic boron carbide. The content of the cerium boride does not affect greatly on flexibility strength. However，it gives much effect on fracture toughness. When the content of the cerium boride is 4wt%, the fracture toughness reaches its supreme value of 5.06MPa.m1/2, which is improved nearly 37.5% compared to monolithic boron carbide materials. The main fracture way of B4C-CeB6 composite is intercrystalline rupture, while the transcrystalline rupture is minor. It appears that this change of fracture mode gives rise to the improvement of the fracture toughness.

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Wang, Xiao Xiang, Wei Qi Wang, Wei Qing Li, Feng Li Li, and Yu Lan Yang. "The Effect of Heat Treatment System on Mechanical Properties of Titanium Alloy BTi-6554." Materials Science Forum 618-619 (April 2009): 177–80. http://dx.doi.org/10.4028/www.scientific.net/msf.618-619.177.

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The effects of solution and aging treatment on the mechanical properties of BTi-6554 alloy titanium were investigated. The results showed: As to βsolution and aging treatment, the increase of fracture toughness is quite conspicuous as the solution temperature was raised, but the change of strength and plasticity is not obvious; As to (α+β) solution and aging treatment, the decline of fracture toughness and plasticity is quite conspicuous as the solution temperature increased, but the strength increased. The strength of (α+β) solution and aging treatment is higher than that of βsolution and aging treatment, but the fracture toughness is relatively lower. As the aging temperature increased, the strength of the alloy gradually decreased, but the plasticity and fracture toughness gradually improved and the improvement of fracture toughness is quite conspicuous. A better combination of strength-toughness-ductibility could be obtained under the heat treatment as solution at 900~930 oC and aging treatment at 560~590 oC.

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Zhang, Peng, Jia Wang, Qingfu Li, Jinyi Wan, and Yifeng Ling. "Mechanical and fracture properties of steel fiber-reinforced geopolymer concrete." Science and Engineering of Composite Materials 28, no. 1 (2021): 299–313. http://dx.doi.org/10.1515/secm-2021-0030.

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Abstract In this study, the effects of steel fibers on the mechanical properties of the geopolymer concrete – compressive, splitting tensile, and flexural strength; compressive elastic modulus; and fracture properties – were evaluated. Milling steel fibers were incorporated into the geopolymer concrete, and the volume fraction of the steel fibers was varied from 0 to 2.5%. Fly ash and metakaolin were chosen as the geopolymer precursors. Fracture parameters – critical effective crack length, initial fracture toughness, and unstable fracture toughness – were measured by a three-point bending test. The results indicated that all the mechanical properties of the geopolymer concrete are remarkably improved by the steel fibers with the optimum dosage. When the steel fiber content was under 2%, the cubic and axial compressive strength and the compressive elastic modulus increased. The inclusion of 2% steel fibers enhanced the cubic and axial compressive strength and the compressive elastic modulus by 27.6, 23.7, and 47.7%, respectively. When the steel fiber content exceeded 2%, the cubic and axial compressive strength and the compressive elastic modulus decreased, having values still higher than those of the geopolymer concrete without steel fibers. The splitting tensile strength and flexural strength of the concrete were enhanced with increasing steel fiber content. When the steel fiber content was 2.5%, the increment of the splitting tensile strength was 39.8%, whereas that of the flexural strength was 134.6%. The addition of steel fibers effectively improved the fracture toughness of the geopolymer concrete. With 2.5% steel fibers, the initial fracture toughness had an increase of 27.8%, and the unstable fracture toughness increased by 12.74 times compared to that of the geopolymer concrete without the steel fibers.

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Hsieh, Tsung-Han, Ming-Yuan Shen, Yau-Shian Huang, Qi-Qian He, and Hsuan-Chih Chen. "Mechanical Properties of Glass Bead-Modified Polymer Composite." Polymers and Polymer Composites 26, no. 1 (2018): 35–44. http://dx.doi.org/10.1177/096739111802600105.

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This present work investigated the adhesive effect of the material properties and fracture toughness of a thermosetting epoxy polymer modified with micron-sized glass beads. Various surface treatments were used to modify the surfaces of the glass beads in order to consider the effect of the glass bead particle/epoxy adhesion on the material properties and toughness of the polymer-based composites. Adding glass beads into polymer resulted in an increase in the modulus. The maximum value of the modulus was obtained for the polymer composite modified with well-bonded glass beads. The addition of the glass beads to polymers leads to a significant improvement in the fracture toughness. The particle/matrix adhesion strongly affects the toughness of the glass bead-modified polymers. The coupling agent silane treatment and release agent Frekote treatment caused well-bonded particles and poorly-bonded particles with the epoxy matrix. Both of the surface treatments result in a significant increase in the toughening performance. Toughening mechanisms of plastic void growth and crack deflection caused by the addition of the glass beads were found on the fracture surfaces of the tested specimens.

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Fereidoon, Abdolhossein, Lia Mottahedin, and Sara Tahan Latibari. "Investigation of fracture toughness parameters of epoxy nanocomposites for different crack angles." Journal of Polymer Engineering 32, no. 4-5 (2012): 311–17. http://dx.doi.org/10.1515/polyeng-2011-0120.

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Abstract The effects of single-walled carbon nanotubes (SWCNTs) on the mechanical properties of nanocomposites with epoxy matrix were studied, with the emphasis on fracture toughness under tensile loading conditions. It has been demonstrated that adding CNTs into polymer-based materials can improve the mechanical properties of this material. CNTs possess a certain potential to improve the fracture toughness of epoxy systems due to their mechanical properties and increase the fracture toughness of nanocomposites. Since the fracture toughness parameters were best manifested in the scaling properties and were the main parameters, the angles of different cracks have been simulated in a 3D finite element framework and the effects of different angles of crack, on the fracture toughness of polymers, have been modeled and investigated. The simulations are run for different bias angles. The influence of angle, the crack lengths and the variations of different lengths of nanocomposite in different volume fractions (vol%) are investigated. That is to say, at first, nanocomposites had a significantly higher fracture toughness compared to the pure epoxy. We found that nanocomposites, in the presence of SWCNTs, had a greater effect on fracture toughness of nanocomposites in a greater volume of fractions. Also, the nanocomposites exhibited a significant increase in fracture toughness, with zero angle of crack compared with greater angles. In addition, it is found that at a constant volume fracture, fracture toughness, increases by increasing crack lengths.

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Jun, Liu, Liu Su, Chen Zhigang, Zhou Fei, and Chang Min Suh. "Effect of Y-TZP on Mechanical Properties of Al2O3-TiB2 Ceramics." International Journal of Modern Physics B 17, no. 08n09 (2003): 1279–84. http://dx.doi.org/10.1142/s0217979203018879.

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The effect of Y-TZP additive on the mechanical properties of Al2O3-TiB2 ceramics was investigated. The results indicate that Y-TZP additive can enhance the flexure strength and fracture toughness of Al2O3-TiB2 ceramics, but has little effect on their hardness. The maximum bending strength of Al2O3-TiB2 and Al2O3-TiB2-Y-TZP ceramics are at 20vol% TiB2 content. The maximum fracture toughness for two kinds of ceramics all are at 30vol% TiB2 content. The bending strength and fracture toughness as well as impact resistance of Al2O3-TiB2-Y-TZP ceramics are higher than those of Al2O3-TiB2 ceramics. The cutting behaviors of two kinds of ceramics are satisfactory. When the ceramic cutting tools are applied to continuous cutting, the wear resistance of cutting tools increases as an increase in TiB2 content. But when they are applied to intermittent cutting, the serving life of ceramic cutting tools is mainly governed by their fracture toughness, The mainly failure mechanism of intermittent cutting is micro-chipping.

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Liu, Yongwei, Fuwen Chen, Guanglong Xu, Yuwen Cui, and Hui Chang. "Correlation between Microstructure and Mechanical Properties of Heat-Treated Ti–6Al–4V with Fe Alloying." Metals 10, no. 7 (2020): 854. http://dx.doi.org/10.3390/met10070854.

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The microstructure and mechanical properties of a newly developed Fe-microalloyed Ti–6Al–4V titanium alloy were investigated after different heat treatments. The volume fraction and the morphological features of the lamellar α phase had significant effects on the alloy’s mechanical performance. A dataset showing the relationship between microstructural features and tensile strength, elongation, and fracture toughness was developed. A high aging temperature resulted in high plasticity and fracture toughness, but relatively low strength. The high strength favored the fine α and the slender β. The high aspect ratio of lamellar α led to high strength but low fracture toughness. The alloy with ~84 vol % α exhibited the highest strength and lowest fracture toughness because the area of its α/β-phase interface was the highest. Optimal comprehensive mechanical performance and heat-treatment procedures were thus obtained from the dataset. Optimal tensile strength, yield strength, elongation, and fracture toughness were 999 and 919 MPa, 10.4%, and 94.4 MPa·m1/2, respectively.

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Sun, Zhu Feng, and Ling Yun Xie. "Impact of Metallic Foam’s Microstructure to its Mechanical Property." Advanced Materials Research 634-638 (January 2013): 2808–12. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.2808.

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Explored the influence of pore structure of foam metal material on mechanical behavior of fracture. Discuss fracture toughness of several different micro geometric structure of foam metal material with finite element method. The author's calculations showed, microstructure and loading mode has an important effect on the fracture toughness of the foam metal material. due to ignoring the effects of cell structure on the mechanical properties of materials, the classic fracture toughness criterion -crack tip opening displacement (COD) is incomplete, it would be more efficient to take opening displacement change rate of the crack-tip as the parameter to characteristic the metallic foam material fracture toughness.

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Kim, Seong-Eun, and In-Jin Shon. "Mechanical Properties and Rapid Sintering of Nanostructured WC-Al2O3-Al Hard Materials." Journal of Nanoscience and Nanotechnology 21, no. 7 (2021): 3929–33. http://dx.doi.org/10.1166/jnn.2021.19244.

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Nanostructured WC-Al2O3-Al composites was sintered using rapid high-frequency induction heated sintering (HFIHS) and the mechanical properties such as hardness and fracture toughness with consolidation were investigated. The HFIHS method induced a very fast densification nearly at the level of theoretical density and successfully prohibited grain growth, resulting in nano-sized grains. The fracture toughness was improved due to the consolidation facilitated by adding Al to WC-Al2O3 matrix. The WC-Al2O3 composites added with 5 and 10 vol.% Al showed higher hardness and fracture toughness compared with that of WC-Al2O3.

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Tohgo, Keiichiro, and Takayuki Kawaguchi. "Influence of Material Composition on Mechanical Properties and Fracture Behavior of Ceramic-Metal Composites." Key Engineering Materials 297-300 (November 2005): 1516–21. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.1516.

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In order to estimate distribution of mechanical properties and fracture toughness in ceramic-metal functionally graded materials (FGMs), mechanical properties and fracture behavior have been investigated on non-graded ceramics-metal composites which correspond to each region of FGMs. The materials are fabricated by powder metallurgy using partially stabilized zirconia (PSZ) and stainless steel (SUS 304). Vickers hardness, Young’s modulus and bending fracture strength were examined on smooth specimens. The Vickers hardness of the composites continuously decreases with an increase in a volume fraction of SUS 304 metal phase, while the Young’s modulus and fracture strength exhibit low values in the composites with balanced composition of each phase. This suggests that the interfacial strength between the ceramic and metal phases is very low. Fracture toughness tests are conducted by three-point-bending on rectangular specimens with a sharp edgenotch. In contrast with the Young’s modulus and fracture strength, the fracture toughness obtained for the composites increases with an increase in a volume fraction of SUS 304 metal phase. The fracture toughness of the composites is slightly lower than that obtained previously by stable crack growth in a PSZ-SUS 304 FGM. The difference in fracture toughness between the composites and FGM seems to be attributed to the residual stress created during fabrication of the FGM.

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Reynolds, T. D., M. Acosta, and David R. Johnson. "Processing and Mechanical Properties of RuAl-Based Alloys." Materials Science Forum 539-543 (March 2007): 1469–74. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.1469.

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Alloys of Ru-Al-Cr with compositions between Ru-10Al-35Cr and Ru-3Al-39Cr (at.%) were directionally solidified and heat treated to produce single phase hcp-Ru(Cr,Al) and two phase B2-hcp microstructures. The room temperature fracture toughness, tensile behavior, and cyclic oxidation behavior at 1100°C were investigated and compared to previous results measured from RuAl and Ru-Al-Mo alloys. For microstructures consisting of a Ru(Cr,Al) matrix with fine RuAl precipitate, a good room temperature fracture toughness, tensile ductility, and oxidation resistance at 1100°C were measured.

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Wu, Xi Wang, Jian Zhong Xiao, Feng Xia, Yong Gang Hu, and Zhou Peng. "Preparation and Mechanical Properties of Carbon Nanotubes Reinforced Alumina Ceramic Composite." Advanced Materials Research 239-242 (May 2011): 2721–27. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.2721.

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How to uniformly disperse carbon nanotubes (CNTs) and densely sinter green body are the key issues to prepare carbon nanotubes reinforced alumina (Al2O3) composite. We prepare CNTs-Al2O3 powder by shearing extruding dispersion method, and then obtain CNTs-Al2O3 composite by hydrogen atmosphere pressureless sintering. 93% of the relative increased fracture toughness can be achieved, when the CNTs content of composite is 1%. Because of Absorbing energy by pulling CNTs out from alumina matrix and refining grain by CNTs bundles sitting along alumina grain, the fracture toughness is improved obviously. By XRD and SEM analysis, the residual tensile stress which is caused by embedding CNTs into alumina matrix also plays an important role for the increase of fracture toughness.

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Li, Hong Bo, Jing Wang, Han Chi Cheng, Chun Jie Li, and Xing Jun Su. "Effect of Tempering Temperature on Mechanical Properties of High Strength Wear Resistant Cast Steel." Advanced Materials Research 791-793 (September 2013): 440–43. http://dx.doi.org/10.4028/www.scientific.net/amr.791-793.440.

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This paper mainly studied the high temperature quenching oil quenching, tempering temperature on the influence of high strength steel mechanical properties of wear resistant. The results show that high strength and toughness wear-resistant cast steel with 880°C× 30min after oil quenching, the hardness of 38.6HRC steel, the impact toughness value reaches 40.18J/cm2. After 200°C, 400°C and 600°C tempering, with the increase of the tempering temperature, the hardness decreased linearly, as by 600°C tempering, the hardness has been reduced to 22.3HRC. Impact toughness with the tempering temperature, the overall upward trend, the impact toughness of some reduced at 400°C, the highest impact toughness value reaches 113.34J/cm2. From the fracture morphology can be seen, with the increase of tempering temperature, ductile fracture increased, by 600°C tempering is dimple fracture, obviously can not see the traces of brittle fracture.

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Kwon, Seok Jin, Dong Hyung Lee, Jung Won Seo, and Hyun Mu Hur. "Mechanical Properties of Railway Wheel for Standard Reinforcement." Advanced Materials Research 26-28 (October 2007): 1247–50. http://dx.doi.org/10.4028/www.scientific.net/amr.26-28.1247.

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For the high quality of wheel, the railway wheel has standardized such as UIC, KS, and JIS code but the chemical composition, the mechanical property and the hardness is merely requested. Although the standard of railway wheel has sustained, the damages of railway wheel have been occurred in service running. Because of wheel damage with spalling, shelling and thermal crack, the maintenance cost for the railway wheel has increased. In order to reduce wheel damage, it is necessary to reinforce the standard of railway wheel. In present study, the fracture mechanics characteristics of railway wheel such as threshold stress intensive factor, fracture toughness and impact energy depended on temperature have tested. The result shows that the standard of railway wheel has to supplement fracture toughness and impact energy depended on low temperature in order to reduce the wheel damage.

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Jordan, William M., Walter L. Bradley, and Richard J. Moulton. "Relating Resin Mechanical Properties to Composite Delamination Fracture Toughness." Journal of Composite Materials 23, no. 9 (1989): 923–43. http://dx.doi.org/10.1177/002199838902300904.

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Kim, Jang Kyo, Naveed A. Siddiqui, Ricky S. C. Woo, Christopher K. Y. Leung, and Arshad Munir. "Carbon Fibre-Organoclay Hybrid Epoxy Composites: Fracture Behaviours and Mechanical Properties." Key Engineering Materials 312 (June 2006): 179–86. http://dx.doi.org/10.4028/www.scientific.net/kem.312.179.

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The fracture resistance and mechanical properties of carbon fiber reinforced composites (CFRPs) containing organoclay-filled epoxy resin are studied. The XRD analysis and TEM examination revealed well-dispersed organoclay in the epoxy matrix displaying a mixture of exfoliation and intercalation. There was a significant improvement in flexural modulus and a marginal reduction in flexural strength of epoxy matrix due to the incorporation of organoclay. The quasi-static fracture toughness of epoxy increased nearly 60% with the addition of 3wt% clay, but there was a 45% drop in impact fracture toughness with 1wt% clay. When CFRPs were fabricated with the clay-modified epoxy resin, both the flexural modulus and strength of the hybrid composites showed negligible changes due to a few wt% of organoclay in the matrix. The interlaminar crack growth stability and the corresponding mode I interlaminar fracture toughness of the hybrid composites with organoclay improved substantially compared to those with carbon fibres only. The hybrid composites typically presented rough matrix surface associated with pinning and crack tip bifurcation, whereas the composite made from neat epoxy showed a smooth river line structure which is characteristic of brittle epoxy. The correlation between the composite interlaminar fracture properties and the toughness of modified matrix is discussed.

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Baer, Wolfram. "Performance of Modern DCI Materials – Investigation of Microstructural, Temperature and Loading Rate Effects on Mechanical and Fracture Mechanical Properties." Materials Science Forum 783-786 (May 2014): 2244–49. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2244.

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Design and safety assessment of advanced ductile cast iron (DCI) components like windturbines or transport and storage casks for radioactive materials require appropriate material data interms of strength and fracture toughness. Therefore, it is of vital importance to characterize andunderstand the deformation, damage and fracture behaviour of DCI which may substantially changefrom ductile to brittle by increasing loading rate, decreasing temperature and/or increasing stresstriaxiality. This paper reports on recent BAM investigations on different qualities of the widely usedDCI grade EN-GJS-400 with varying pearlite shares (none and 18 % respectively). The focus wason the influences of microstructure, temperature (ambient and -40 °C) and loading rate (quasi-staticto crash) on strength (YS, UTS, flow curve) and fracture mechanical properties (R-curve, crackinitiation toughness, fracture toughness). Systematic metallographical and fractographical analyseswere performed accompanying the whole test program and a systematics of specific damagebehaviour and fracture mechanisms was derived from the results.

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Markandan, Kalaimani, Jit Kai Chin, and Michelle T. T. Tan. "Study on Mechanical Properties of Zirconia-Alumina Based Ceramics." Applied Mechanics and Materials 625 (September 2014): 81–84. http://dx.doi.org/10.4028/www.scientific.net/amm.625.81.

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This paper describes the characterisations of ceramic composites consisting of different compositions of alumina and zirconia. The material characterisations were performed from the aspects of densification, hardness and fracture toughness. The surface morphology and elemental composition of the composite were studied using SEM and EDX respectively. As for physical properties, the highest attainable hardness and fracture toughness were 11.35 GPa and 3.41 MPa m0.5respectively for ceramic composite consisted of 80 wt % Zr and 20 wt% Al. Sintering at 1150oC assisted in the densification of ceramics.

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Carrasquero Rodriguez, Edwuin Jesus, Jaime Moises Minchala Marquino, Byron Ramiro Romero Romero, Luis Marcelo Lopez Lopez, and Jorge Isaac Fajardo Seminario. "Determination of fracture toughness and elastic module in materials based silicon nitride." Ingeniería Investigación y Tecnología 20, no. 4 (2019): 1–13. http://dx.doi.org/10.22201/fi.25940732e.2019.20n4.048.

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The knowledge of the mechanical properties of any material subjected to loads is necessary for its use in structural applications. Silicon nitride (Si3N4) ceramics are well-known materials used in engineering applications due to their outstanding combination of high strength and fracture toughness. The most studied mechanical properties of Si3N4 are hardness, fracture toughness and mechanical resistance. Recent advances in the production processes that incorporate high purity rare earth elements as sintering additives have improved these mechanical properties. Using Vickers indentation method, the elastic module and fracture toughness of Si3N4 based materials modified with La2O3, Y2O3 and Al2O3 were determined as a function of the cracking system type that prevails under the effect of load. The results indicate that adding rare earth to the matrix increased the fracture toughness the Si3N4 base ceramic Samples containing La2O3+Y2O3 showed higher values of fracture toughness than the ones with Al2O3+La2O3, regardless of the equation used in the calculations. Meanwhile the elastic module decrease approximately 100 GPa for both types of nitrides by the effect of the temperature.

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Maier, Marcus, Alireza Javadian, Nazanin Saeidi, Cise Unluer, Hayden K. Taylor, and Claudia P. Ostertag. "Mechanical Properties and Flexural Behavior of Sustainable Bamboo Fiber-Reinforced Mortar." Applied Sciences 10, no. 18 (2020): 6587. http://dx.doi.org/10.3390/app10186587.

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In this study, a sustainable mortar mixture is developed using renewable by-products for the enhancement of mechanical properties and fracture behavior. A high-volume of fly ash—a by-product of coal combustion—is used to replace Portland cement while waste by-products from the production of engineered bamboo composite materials are used to obtain bamboo fibers and to improve the fracture toughness of the mixture. The bamboo process waste was ground and size-fractioned by sieving. Several mixes containing different amounts of fibers were prepared for mechanical and fracture toughness assessment, evaluated via bending tests. The addition of bamboo fibers showed insignificant losses of strength, resulting in mixtures with compressive strengths of 55 MPa and above. The bamboo fibers were able to control crack propagation and showed improved crack-bridging effects with higher fiber volumes, resulting in a strain-softening behavior and mixture with higher toughness. The results of this study show that the developed bamboo fiber-reinforced mortar mixture is a promising sustainable and affordable construction material with enhanced mechanical properties and fracture toughness with the potential to be used in different structural applications, especially in developing countries.

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Fei, Yu Huan, Chuan Zhen Huang, Han Lian Liu, and Bin Zou. "Mechanical Properties of Al₂O₃-TiN Nanocomposite Ceramic Tool Materials." Key Engineering Materials 499 (January 2012): 108–13. http://dx.doi.org/10.4028/www.scientific.net/kem.499.108.

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Al2O3-TiN nanocomposite ceramic tool materials were fabricated by hot-pressing technique and the mechanical properties were measured. Mechanical properties such as room temperature flexural strength, Vickers hardness and fracture toughness were measured through three-point bending test and Vickers indentation. The effects of the content of nano-scale TiN, sintering temperature and holding time on the mechanical properties were investigated. The results shows that the addition of nano-scale TiN can improve the mechanical properties of alumina ceramics. Both the flexural strength and the fracture toughness first increased then decreased with an increment in the content of nano-scale TiN. Both the Vickers hardness and the fracture toughness increased with an increment in the sintering temperature. The flexural strength increased with an increment in the holding time, while the fracture toughness decreased with an increment in the holding time. The composites with only nano-scale TiN have the highest Vickers hardness for the holding time of 30min, while the hardness of the composites with nano-scale TiN and micro-scale TiN decreased with an increment in the holding time.

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Shimada, Yusuke, Yoichi Kayamori, Shohei Nishida, Mitsuhiro Matsuda, and Kazuki Takashima. "Micromechanical Characterisation of Microstructure in Weld Heat Affected Zone of Structural Steel." Key Engineering Materials 525-526 (November 2012): 585–88. http://dx.doi.org/10.4028/www.scientific.net/kem.525-526.585.

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Microstructures in the weld heat affected zone (HAZ) can cause a decrease in fracture toughness, and evaluating the effect of microstructures on fracture toughness is helpful in understanding the cause of the fracture toughness decrease. In this study, micro-sized tensile specimens were sampled from base metal and HAZ, and the mechanical properties and fracture behaviours of different steel microstructures were directly investigated by micro-sized mechanical testing.

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Eun, Jong H., Bo K. Choi, Sun M. Sung, Min S. Kim, and Joon S. Lee. "Effect of toughened polyamide-coated carbon fiber fabric on the mechanical performance and fracture toughness of CFRP." Journal of Composite Materials 55, no. 20 (2021): 2721–38. http://dx.doi.org/10.1177/0021998321999458.

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In this study, carbon/epoxy composites were manufactured by coating with a polyamide at different weight percentages (5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%) to improve their impact resistance and fracture toughness. The chemical reaction between the polyamide and epoxy resin were examined by fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray photoelectron spectroscopy. The mechanical properties and fracture toughness of the carbon/epoxy composites were analyzed. The mechanical properties of the carbon/epoxy composites, such as transverse flexural tests, longitudinal flexural tests, and impact tests, were investigated. After the impact tests, an ultrasonic C-scan was performed to reveal the internal damage area. The interlaminar fracture toughness of the carbon/epoxy composites was measured using a mode I test. The critical energy release rates were increased by 77% compared to the virgin carbon/epoxy composites. The surface morphology of the fractured surface was observed. The toughening mechanism of the carbon/epoxy composites was suggested based on the confirmed experimental data.

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Fan, Chun Ping, Zi Qiao Zheng, Min Jia, Ji Fa Zhong, and Bin Cheng. "Microstructure and Mechanical Properties of Al-Li Alloy 2397-T87 Rolled Plate." Materials Science Forum 788 (April 2014): 249–57. http://dx.doi.org/10.4028/www.scientific.net/msf.788.249.

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The microstructure, tensile property and fracture toughness of Al-Li alloy 2397-T87 rolled plate were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, tensile and plane-strain fracture toughness tests. The results show that a pronounced texture variation through the plate thickness was found. Near the surface, Goss texture dominated. While in the center of the plate, typical β fiber texture and a scattering of cube texture were observed. And the subsurface layer exhibited a very weak texture. From the center to the subsurface, the fraction of β fiber texture and cube texture decreased. In contrast, the fraction of shear type texture reaching the maximum in subsurface layer increased. The tensile properties in different layers along the thickness direction were inhomogeneous. The strengths near the surface were lower than those in the center. And the through-thickness strength properties variation in the rolling direction was more remarkable than that in the long transverse direction. In the same thickness layer, the fracture toughness and the strengths were anisotropic. The strengths in the rolling direction were higher than those in the long transverse direction and the short transverse direction, and the strengths in the short transverse direction were the lowest. The fracture toughness in L-T orientation was the highest, followed by that in T-L orientation, and the fracture toughness in S-L orientation was the lowest.

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Zhang, Lian Meng, Li Chun Yu, Dao Ren Gong, and Qiang Shen. "Fabrication and Mechanical Properties of TZ-3Y20A /Mo Multilayer Composites." Materials Science Forum 492-493 (August 2005): 605–8. http://dx.doi.org/10.4028/www.scientific.net/msf.492-493.605.

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In the present work, TZ-3Y20A/Mo multilayer composites were prepared by sedimentation method. Appropriate settling parameters were chosen and green bodies of multilayer composites were obtained by settling TZ-3Y20A powder and Mo powder in turn according to the designed individual layer thickness. Then green laminates were hot pressed at 1773K for an hour under the pressure of 20MPa. Three-point Bending and Single Edge Notched Beam (SENB) tests were adopted to evaluate the flexure strength and fracture toughness of the samples. The results showed that, compared to TZ-3Y20A ceramics, the fracture toughness and the work of fracture increased due to the layered structure. The microstructure and crack deflection of the fracture surface of the laminated composites was also observed by optical microscopy.

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Yan, Xingheng, Xingui Zhou, and Honglei Wang. "Effect of Additive Ti3SiC2 Content on the Mechanical Properties of B4C–TiB2 Composites Ceramics Sintered by Spark Plasma Sintering." Materials 13, no. 20 (2020): 4616. http://dx.doi.org/10.3390/ma13204616.

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B4C–TiB2 composite ceramics with ultra-high fracture toughness were successfully prepared via spark plasma sintering (SPS) at 1900 °C using B4C and Ti3SiC2 as raw materials. The results showed that compared with pure B4C ceramics sintered by SPS, the hardness of B4C–TiB2 composite ceramics was decreased, but the flexural strength and fracture toughness were significantly improved; the fracture toughness especially was greatly improved. When the content of Ti3SiC2 was 30 vol.%, the B4C–TiB2 composite ceramic had the best comprehensive mechanical properties: hardness, bending strength and fracture toughness were 27.28 GPa, 405.11 MPa and 18.94 MPa·m1/2, respectively. The fracture mode of the B4C–TiB2 composite ceramics was a mixture of transgranular fracture and intergranular fracture. Two main reasons for the ultra-high fracture toughness were the existence of lamellar graphite at the grain boundary, and the formation of a three-dimensional interpenetrating network covering the whole composite.

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Yi, Ting. "Mechanical properties of a hierarchical honeycomb with sandwich walls." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 16 (2016): 2765–75. http://dx.doi.org/10.1177/0954406215602284.

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The in-plane compressive collapse and fracture toughness of a hierarchical hexagonal honeycomb with sandwich walls consisting of corrugated cores are studied by using finite element method. Its near-optimal configuration is identified by maximizing its elastic limit, which is determined by three competing failure modes including plastic yielding of the larger struts, or elastic wrinkling of the face sheets of the larger struts, or elastic buckling of the smaller struts. The overall mechanical properties of the optimal hierarchical honeycomb, including the Young’s modulus, elastic limit, peak strength, and fracture toughness are obtained from finite element method simulation and compared with analytical predictions, and the discrepancy between the two is explained. The optimal hierarchical honeycomb is found to be superior to its equivalent mass first-order honeycomb in all the mechanical properties listed above when the relative density is low (about 10%). Moreover, the Young’s modulus, elastic limit and peak strength under plastic failure mode, and the fracture toughness of this optimal hierarchical honeycomb are shown to depend linearly upon its relative density. This paper provides additional insights into hierarchical cellular materials.

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Bartsch, Marion, Iulian Mircea, Jens Suffner, and Bernd Baufeld. "Interfacial Fracture Toughness Measurement of Thick Ceramic Coatings by Indentation." Key Engineering Materials 290 (July 2005): 183–90. http://dx.doi.org/10.4028/www.scientific.net/kem.290.183.

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The basic requirement for the use of a ceramic coating is sufficient adhesion to its substrate. A measure of the adhesive properties of a coating is the interfacial fracture toughness. The test method applicable for interfacial fracture toughness measurements depends on the mechanical properties of the material system and the geometry of the test piece. In this work, indentation methods have been evaluated for the estimation of the fracture toughness of ceramic thermal barrier coatings on metallic substrates. Coatings of 100 to 300 µm thickness were applied by electron beam – physical vapour deposition. The performed test types were Vickers indentation at the interface of polished cross sections of the coating system and Rockwell indentation with a brale C indenter, penetrating the coating perpendicular to the surface. Both tests generate delamination, in which the delamination crack length corresponds to the interfacial fracture toughness. Fracture surfaces and cross sections of the fractured coatings were investigated by optical and scanning electron microscope. Determined fracture toughness values are discussed with respect to the loading conditions in the test and the fracture process – i.e. interaction between indenter and coating system and the crack propagation path.

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Chen, Jian, Wei Liu, Xin Deng, and Shanghua Wu. "Effects of Mo and Vc on the microstructure and properties of nano-cemented carbides." Science of Sintering 48, no. 1 (2016): 41–50. http://dx.doi.org/10.2298/sos1601041c.

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In this study, four unique groups of nano-cemented carbides with 8 wt.% Co and trace amount of Mo and VC have been successfully synthesized. The effect of Mo and VC has been investigated comprehensively on both the microstructure and mechanical behavior of nano-cemented carbide. The results show that Mo significantly increases hardness but decreases the fracture toughnesses and VC slightly increases hardness and strongly increases fracture toughness of nano-cemented carbide. It is found that the optimum Mo and VC contents are both 0.5 wt.%. The average WC grain size is about 370 nm. The hardness is about 2350 HV30 and the fracture toughness is about 11.2 MPam-1/2.

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Alam, M. R., A. S. J. Swamidas, J. Gale, and K. Munaswamy. "Mechanical and physical properties of slate from Britannia Cove, Newfoundland." Canadian Journal of Civil Engineering 35, no. 7 (2008): 751–55. http://dx.doi.org/10.1139/l08-042.

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The experimental investigation described in this study was carried out to determine the physical and mechanical properties (elastic moduli, Poisson’s ratio, compressive and tensile strengths, hardness and plane strain fracture toughness) of slate quarried from Britannia Cove, Bonavista, Newfoundland, Canada. Microscopic observations were carried out to determine layers’ orientation and thickness and the grain boundaries. All tests were carried out according to American Society for Testing and Materials (ASTM) and International Society for Rock Mechanics (ISRM) procedures. The results obtained from this investigation were compared with those obtained from other published results for slate, mined from different parts of the world. It is seen that the present test results are compatible with other published results except for fracture toughness and direct tension tests. In fracture toughness tests, the calculated values using accepted empirical equations were much higher than the numerically computed values using finite element analysis (FEA). For the case of direct and indirect tension tests, the differences between our experimental values and previously published results were quite large.

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Hu, An Min, Kai Ming Liang, Feng Zhou, Fei Peng, and Guoliang Wang. "Crystallization and Mechanical Properties of Spodumene-Diopside Glass Ceramics." Key Engineering Materials 280-283 (February 2007): 1639–42. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.1639.

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The mechanical properties of spodumene-diopside glasses ceramics with 4-12% TiO2 were investigated. The main crystalline phases precipitated were eucryptite, β-spodumene and diopside. As TiO2 content increasing, the morphology of glass ceramics transformed from coarse to fine microstructure, then to reverse. The flexural strength, elastic moduli, Vickers hardness and fracture toughness of the glass-ceramics were measured. The flexural strength of glass–ceramics containing 9%TiO2 was 198MPa, the Young’s modulus and fracture toughness were 91.3GPa and 2.3 MPa·m1/2 respectively. It was indicated that the mechanical properties were correlated with crystallization and morphology of glass ceramics

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Chou, Y.-S., J. W. Stevenson, T. R. Armstrong, J. S. Hardy, K. Hasinska, and L. R. Pederson. "Microstructure and Mechanical Properties of Sm1-xSrxCo0.2Fe0.8O3." Journal of Materials Research 15, no. 7 (2000): 1505–13. http://dx.doi.org/10.1557/jmr.2000.0216.

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The room temperature mechanical properties of a mixed conducting perovskite Sm1?xSrxCo0.2Fe0.8O3 (x = 0.2 to 0.8) were examined. Density, crystal phase, and microstructure were characterized. It was found that the grain size increased abruptly with increasing Sr content. Mechanical properties of elastic modulus, microhardness, indentation fracture toughness, and biaxial flexure strength were measured. Young's modulus of 180–193 GPa and shear modulus of 70–75 GPa were determined. The biaxial flexure strength was found to decrease with increasing Sr content from ∼70 to ∼20 MPa. The drop in strength was due to the occurrence of extensive cracking. Indentation toughness showed a similar trend to the strength in that it decreased with increasing Sr content from ∼1.1 to ∼0.7 MPa m1/2. In addition, fractography was used to characterize the fracture behavior in these materials.

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Smith, Ryan Scott, Ting Y. Tsui, and Paul S. Ho. "Effects of ultraviolet radiation on ultra-low-dielectric constant thin film fracture properties." Journal of Materials Research 24, no. 9 (2009): 2795–801. http://dx.doi.org/10.1557/jmr.2009.0346.

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The effects of ultraviolet (UV) radiation on ultra-low-k dielectric (ULK) thin film fracture toughness were studied. This work discusses both critical and subcritical crack growth behavior under different environments. The critical fracture toughness was measured as a function of applied phase angle by using the four-point bend flexure and mixed-mode double cantilever beam techniques. Results of critical fracture toughness obtained under different loading configurations and phase angles were found to increase with the UV treatment time. In contrast, mode I subcritical fracture toughness thresholds and the crack propagation velocity appeared to be insensitive to UV curing processes. This study revealed that subcritical fracture toughness values reduced with the moisture concentration in the environment.

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Xiang, Song, Jiang Ping Wang, Yu Ling Sun, Yong You Yan, and Shi Gang Huang. "Effect of Ageing Process on Mechanical Properties of Martensite Precipitation-Hardening Stainless Steel." Advanced Materials Research 146-147 (October 2010): 382–85. http://dx.doi.org/10.4028/www.scientific.net/amr.146-147.382.

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17-4PH precipitation-hardening martensite stainless steel is an important commercially available stainless steel. And the mechanical properties of this steel are very sensitive to quenching and aging process. In this paper, the effects of aging process on mechanical properties of this steel were investigated. The results show that the microstructure of this steel consists of quenched martensite, tempered martensite and precipitates. With the increase of the aging temperature, the strength decreases and the toughness increase. And the fracture mode of this steel transforms brittle fracture into toughness fracture.

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Nambu, Shoichi, and Manabu Enoki. "Evaluation of Mechanical Properties of Alumina Green Compact during Sintering at Relative Low Temperature." Key Engineering Materials 297-300 (November 2005): 945–50. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.945.

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Recently, ceramics was used extensively as structural materials and ceramics components became larger and more complex. Fracture sometimes occurs during firing because of large and complex shape, and this fracture interrupts manufacturing process. The simulation of sintering has been studied to prevent this fracture. However, it was difficult to simulate fracture process because there was little data on strength of green compact. It is necessary to measure strength during sintering in order to perform a useful simulation. In this study, we measured strength of two kind of alumina green compact during sintering. Three point bending test at elevated temperature was performed and strength was estimated at each temperature. A model for strength at relative low temperature was also proposed using the temperature dependence of specific surface area. Furthermore, fracture toughness test was performed and the relationship between strength and fracture toughness was obtained. Strength at relative low temperature increased with temperature. Fracture toughness was proportional to strength at the temperature range where materials demonstrated brittle fracture manner. Strength of each alumina was analyzed using this model.

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Seo, Dong Seok, Hwan Kim, Kyu Hong Hwang, and Jong Kook Lee. "Dissolution and Mechanical Properties of Sintered Hydroxyapatite Immersed in Water." Key Engineering Materials 317-318 (August 2006): 789–92. http://dx.doi.org/10.4028/www.scientific.net/kem.317-318.789.

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Dissolution of hydroxyapatite (HAp) in distilled water and related mechanical properties were investigated. The commercially obtained stoichiometric HAp powders were used as starting materials. After preparing powder compacts, the disks were sintered at 1200oC for 2 h in air with under moisture protection. The sintered specimens were then placed into 40 ml of 7.4 distilled water. After immersing for certain period of time at 37oC, weight loss, microstructure, and mechanical characteristics of the specimens were investigated. Fracture toughnesses were measured for both sintered and immersed HAp for comparison. Evidence for the surface damage was observed with appearance of micron-level of pitting and grain boundaries dissolved. The value for fracture toughness decreased due to dissolution of the materials.

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Pourhamid, Reza, and Ali Shirazi. "Microstructural evolution and mechanical behaviors of equal channel angular pressed copper." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 1 (2019): 171–79. http://dx.doi.org/10.1177/0954406219872520.

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The mechanical properties including Vickers hardness, tensile properties, fracture toughness, impact toughness and also, the microstructure of copper severely deformed by equal channel angular pressing through route C after two, four, and eight passes at ambient temperature, were studied in the present work. The results indicated that the grains size reduced from 16.7 to 4.8 µm after two and to 2.1 µm after eight passes. This study cleared that because of the recrystallization phenomenon and reducing the effect of stress concentration and increasing the number of grain boundaries, the values of the fracture toughness can increase significantly. For example, fracture toughness increases by 58.4% relative to base metal after eight passes equal channel angular pressing. Also, it was found that the major improvement in tensile properties is achieved after two passes and due to the applied simple shear to the copper, all the equal channel angular pressed specimens have demonstrated an enhanced hardness and impact toughness, in accordance with their number of equal channel angular pressing passes. For example, the Vickers hardness is increased by a factor of 1.98 and impact toughness 58.4% for the extruded material after eight passes.

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Zidan, Saleh, Nikolaos Silikas, Abdulaziz Alhotan, Julfikar Haider, and Julian Yates. "Investigating the Mechanical Properties of ZrO2-Impregnated PMMA Nanocomposite for Denture-Based Applications." Materials 12, no. 8 (2019): 1344. http://dx.doi.org/10.3390/ma12081344.

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Acrylic resin PMMA (poly-methyl methacrylate) is used in the manufacture of denture bases but its mechanical properties can be deficient in this role. This study investigated the mechanical properties (flexural strength, fracture toughness, impact strength, and hardness) and fracture behavior of a commercial, high impact (HI), heat-cured denture base acrylic resin impregnated with different concentrations of yttria-stabilized zirconia (ZrO2) nanoparticles. Six groups were prepared having different wt% concentrations of ZrO2 nanoparticles: 0% (control), 1.5%, 3%, 5%, 7%, and 10%, respectively. Flexural strength and flexural modulus were measured using a three-point bending test and surface hardness was evaluated using the Vickers hardness test. Fracture toughness and impact strength were evaluated using a single edge bending test and Charpy impact instrument. The fractured surfaces of impact test specimens were also observed using a scanning electron microscope (SEM). Statistical analyses were conducted on the data obtained from the experiments. The mean flexural strength of ZrO2/PMMA nanocomposites (84 ± 6 MPa) at 3 wt% zirconia was significantly greater than that of the control group (72 ± 9 MPa) (p < 0.05). The mean flexural modulus was also significantly improved with different concentrations of zirconia when compared to the control group, with 5 wt% zirconia demonstrating the largest (23%) improvement. The mean fracture toughness increased in the group containing 5 wt% zirconia compared to the control group, but it was not significant. However, the median impact strength for all groups containing zirconia generally decreased when compared to the control group. Vickers hardness (HV) values significantly increased with an increase in ZrO2 content, with the highest values obtained at 10 wt%, at 0 day (22.9 HV0.05) in dry conditions when compared to the values obtained after immersing the specimens for seven days (18.4 HV0.05) and 45 days (16.3 HV0.05) in distilled water. Incorporation of ZrO2 nanoparticles into high impact PMMA resin significantly improved flexural strength, flexural modulus, fracture toughness and surface hardness, with an optimum concentration of 3–5 wt% zirconia. However, the impact strength of the nanocomposites decreased, apart from the 5 wt% zirconia group.

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Cui, Ning, Qianqian Wu, Kexiao Bi, Tiewei Xu та Fantao Kong. "Effect of Heat Treatment on Microstructures and Mechanical Properties of a Novel β-Solidifying TiAl Alloy". Materials 12, № 10 (2019): 1672. http://dx.doi.org/10.3390/ma12101672.

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The effect of heat treatment on the microstructures and mechanical properties of a novel β-solidifying Ti–43Al–2Cr–2Mn–0.2Y alloy was investigated. A fully lamellar (FL) microstructure with a colony size of about 100 μm was obtained by heat treatment at 1320 °C/10 min/furnace cooling (FC). A duplex (DP) microstructure with globular γ grains and γ/α2 lamellae was obtained by heat treatment at 1250 °C/4 h/FC. The residual hard–brittle β0 phase was also eliminated after heat treatment. The mechanical properties of the β-solidifying TiAl alloy depended closely on the heat treatment. The FL alloy had better fracture toughness, and the fracture toughness (KIC) value was 24.15 MPa·m1/2. The DP alloy exhibited better ductility, and the room temperature (RT) elongation of the alloy could reach 1%. The elongation of the alloy with different microstructures sharply increased when the temperature increased from 700 to 750 °C, indicating that the microstructure had no effect on the ductile–brittle transition temperature of the β-solidifying TiAl alloy. The fracture morphologies of different tensile specimens were observed. Interlamellar and translamellar fractures were the main fracture features of the FL alloy. Intergranular, translamellar, and interlamellar fractures were the main fracture features of the DP alloy.

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Azhar, Ahmad Zahirani Ahmad, Nik Akmar Rejab, Mohamad Hasmaliza, Mani Maran Ratnam, and Zainal Arifin Ahmad. "The Effects of Cr₂O₃ Addition on Fracture Toughness and Phases of ZTA Ceramic Composite." Advanced Materials Research 620 (December 2012): 35–39. http://dx.doi.org/10.4028/www.scientific.net/amr.620.35.

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Fracture toughness and phases of ceramic composites produced from alumina, yttria stabilized zirconia and chromia oxide system was investigated. The Cr2O3weight percent was varied from 0 wt% to 1.0 wt%. Each batch of composition was mixed, uniaxially pressed 13mm diameter and sintered at 1600 C for 4 h in pressureless conditions. Studies on on their mechanical and physical properties such as Vickers hardness and fracture toughness were carried out. Results show that an addition of 0.6 wt% of Cr2O3produces the best mechanical properties. Results of the highest fracture toughness is 4.73 MPa.m1/2,

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