Journal articles: 'Indents'

1

Tanner, B. K., J. Garagorri, E. Gorostegui-Colinas, M. R. Elizalde, D. Allen, P. J. McNally, J. Wittge, C. Ehlers, and A. N. Danilewsky. "X-ray asterism and the structure of cracks from indentations in silicon." Journal of Applied Crystallography 49, no. 1 (February 1, 2016): 250–59. http://dx.doi.org/10.1107/s1600576715024620.

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The asterism observed in white radiation X-ray diffraction images (topographs) of extended cracks in silicon is investigated and found to be associated with material that is close to breakout and surrounded by extensive cracking. It is a measure of the mechanical damage occurring when the fracture planes do not follow the low-index cleavage planes associated with the crystal structure. It is not related to a propensity for some cracked wafers to shatter during subsequent high-temperature processing. There is no correlation between crack morphology and alignment of an indenter with respect to the orientation of a silicon wafer, the cracks being generated from the apices of the indenter and having threefold symmetry for Berkovich indents and fourfold symmetry for Vickers indents. X-ray diffraction imaging (XRDI) of indents does not reveal this underlying symmetry and the images exhibit a very substantial degree of variation in their extent. This arises because the XRDI contrast is sensitive to the long-range strain field around the indent and breakout reduces the extent of this long-range strain field. Breakout is also detected in the loss of symmetry in the short-range strain field imaged by scanning micro-Raman spectroscopy. Weak fourfold symmetric features at the extremes of the images, and lying along 〈110〉 directions, are discussed in the context of slip generated below the room-temperature indents. Scanning electron microscopy imaging of the region around an indent during focused ion beam milling has permitted the three-dimensional reconstruction of the crack morphology. The surface-breaking Palmqvist cracks are found to be directly connected to the median subsurface cracks, and the presence of extensive lateral cracks is a prerequisite for material breakout at indenter loads above 200 mN. The overall crack shape agrees with that predicted from simulation.

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Bhattacharyya, D., N. A. Mara, P. Dickerson, R. G. Hoagland, and A. Misra. "Transmission electron microscopy study of the deformation behavior of Cu/Nb and Cu/Ni nanoscale multilayers during nanoindentation." Journal of Materials Research 24, no. 3 (March 2009): 1291–302. http://dx.doi.org/10.1557/jmr.2009.0147.

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Nanoscale metallic multilayers, comprising two sets of materials—Cu/Nb and Cu/Ni—were deposited in two different layer thicknesses—nominally 20 and 5 nm. These multilayer samples were indented, and the microstructural changes under the indent tips were studied by extracting samples from underneath the indents using the focused ion beam (FIB) technique and by examining them under a transmission electron microscope (TEM). The deformation behavior underneath the indents, manifested in the bending of layers, reduction in layer thickness, shear band formation, dislocation crossing of interfaces, and orientation change of grains, has been characterized and interpreted in terms of the known deformation mechanisms of nanoscale multilayers.

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Kosinova, Anna, Ruth Schwaiger, Leonid Klinger, and Eugen Rabkin. "Annealing-induced recovery of indents in thin Au(Fe) bilayer films." Beilstein Journal of Nanotechnology 7 (December 28, 2016): 2088–99. http://dx.doi.org/10.3762/bjnano.7.199.

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We employed depth-sensing nanoindentation to produce ordered arrays of indents on the surface of 50 nm-thick Au(Fe) films deposited on sapphire substrates. The maximum depth of the indents was approximately one-half of the film thickness. The indented films were annealed at a temperature of 700 °C in a forming gas atmosphere. While the onset of solid-state dewetting was observed in the unperturbed regions of the film, no holes to the substrate were observed in the indented regions. Instead, the film annealing resulted in the formation of hillocks at the indent locations, followed by their dissipation and the formation of shallow depressions nearby after subsequent annealing treatments. This annealing-induced evolution of nanoindents was interpreted in terms of annihilation of dislocation loops generated during indentation, accompanied by the formation of nanopores at the grain boundaries and their subsequent dissolution. The application of the processes uncovered in this work show great potential for the patterning of thin films.

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Sharma, Hemant Kumar, Raghvendra Sahai Saxena, Aditya Gokhale, Ashok Kapoor, Rajesh Prasad, and Rajesh Kumar Sharma. "Cathodoluminescence Studies of Nanoindented CdZnTe Single Crystal Substrates for Analysis of Residual Stresses and Deformation Behaviour." Defence Science Journal 70, no. 6 (October 12, 2020): 650–55. http://dx.doi.org/10.14429/dsj.70.16383.

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Nanoindentation-induced residual stresses were analysed on (111) Te face CdZnTe single-crystal substrates in this study. CdZnTe substrates were subjected to nanoindentation using cube corner indenter geometry with a peak load of 10 mN. Loading rates of 1 mN/s and 5 mN/s were used in the experiments, with a holding time of 10 s at peak load. Residual stresses on the indented region were analysed from load-displacement curves and explained using dislocation generation and elastic recovery mechanisms. Residual stresses were found to be of compressive type, just on the indented surface. The slip lines along the slip directions of this material were clearly visible in the FE-SEM images of the indents. Indents and surrounding surfaces were characterized using the Cathodoluminescence (CL) technique. CL mapping of the indented surface revealed the dislocation generation and their propagation behaviour just beneath the indenter as well as in the surrounding surfaces. The dislocations act as non-radiative recombination centres and quench the CL intensity locally. Dark lines were explained as the presence of dislocations in the material. CL mapping analysis shows that both the rosette glide and tetrahedral glide of dislocations are the primary deformation mechanisms present in CdZnTe. A rosette structure was observed in the CL mapping. CL spectra at 300 K of un-deformed CdZnTe show a peak at 810 nm wavelength, which corresponds to near-band-edge emission. After indentation, the CL spectra show the peak intensity at 814 nm and 823 nm wavelengths at the edge of the indents created with a loading rate of 1 mN/s and 5 mN/s, respectively. These peak shifts from 810 nm were attributed to the tensile residual stresses present in the indented material.

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Odén, Magnus, Henrik Ljungcrantz, and Lars Hultman. "Characterization of the Induced Plastic Zone in a Single Crystal TiN(001) Film by Nanoindentation and Transmission Electron Microscopy." Journal of Materials Research 12, no. 8 (August 1997): 2134–42. http://dx.doi.org/10.1557/jmr.1997.0286.

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The slip system of TiN at room temperature has been determined to be {110} 〈110〉 by Burgers vector analysis using transmission electron microscopy and slip trace analysis of indents made on a TiN(001) film deposited on a MgO(001) substrate. Both small indents (0.4 mN maximum load) and large indents (40 mN maximum load) were used to study the dislocation structure in TiN. The nucleation of dislocations was investigated using small indents. Further development of the plastic zone was studied using large indents and microhardness indents (1.6 N). The critical resolved shear stress evaluated at the load when pop-in occurs was estimated to be 3.7 GPa, assuming a Hertzian elastic contact. Indents made with a 0.4 mN maximum load show a complex dislocation pattern with loops and straight segments that belong to the same slip system. Dislocations of mixed screw and edge type are dominant. The cascade of dislocations generated during pop-in is likely to nucleate from loops. For larger indents, the plastic zone extends more than three times the diameter of the imprint. The straight dislocations outside the large imprint are arranged in arrays along the 〈100〉 and 〈110〉 directions. A scanning force microscopy study of the surface outside a microhardness indent revealed a raised surface along 〈110〉 and formation of troughs along 〈100〉.

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6

Jonšta, Zdenĕk, Lucie Olejníčková, and Karel Mazanec. "Crack Profile under Vickers Indents." Key Engineering Materials 409 (March 2009): 295–99. http://dx.doi.org/10.4028/www.scientific.net/kem.409.295.

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The present work is focused on complex evaluation of crack profiles, created around Vickers indents in two types of cutting tool ceramics, namely in the Al2O3 + ZrO2 ceramics and -Si3N4. The geometry of Vickers indents is investigated using two different evaluation methods. The first one is based on the application of serial sectioning from the indented specimen surface. The second method consists in the layer removing from plane perpendicular to the indented surface. These evaluation methods are convenient for determine the shape of created cracks and profiles of deformed area developed around the investigated indents. The mentioned methods contribute to the understanding of physical engineering principles resulting from the radial/median and lateral crack formation as the important characteristics influencing the reliable technical application of investigated ceramic materials.

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7

Fei, Xueling, Yijun Zhang, David S. Grummon, and Yang-Tse Cheng. "Indentation-induced two-way shape memory surfaces." Journal of Materials Research 24, no. 3 (March 2009): 823–30. http://dx.doi.org/10.1557/jmr.2009.0101.

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A method is described for the creation of surfaces with cyclically reversible topographical form. Using spherical and cylindrical indenters applied to NiTi shape-memory alloys, an indentation-planarization technique is shown to result in a two-way shape memory effect that can drive flat-to-wavy surface transitions on changing temperature. First, it is shown that deep spherical indents, made in martensitic NiTi, exhibit pronounced two-way cyclic depth changes. After planarization, these two-way cyclic depth changes are converted to reversible surface protrusions, or “exdents.” Both indent depth changes and cyclic exdent amplitudes can be related to the existence of a subsurface deformation zone in which indentation has resulted in plastic strains beyond that which can be accomplished by martensite detwinning reactions. Cylindrical indentation leads to two-way displacements that are about twice as large as that for the spherical case. This is shown to be due to the larger deformation zone under cylindrical indents, as measured by incremental grinding experiments.

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8

Zahedi, Abolfazl, Murat Demiral, Anish Roy, Vladimir I. Babitsky, and Vadim V. Silberschmidt. "Indentation in F.C.C. Single Crystals." Solid State Phenomena 188 (May 2012): 219–25. http://dx.doi.org/10.4028/www.scientific.net/ssp.188.219.

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A three-dimensional crystal-plasticity finite element model of nano-indentation is developed in this paper to analyze deformation of a face-centred cubic (f.c.c.) high-purity single crystal of copper. This model was implemented as a user-deﬁned subroutine in the commercial finite element software ABAQUS/Standard and used to study cases with different crystallographic orientations of the single crystal. The effects of various factors – crystallographic orientation of the indented material, an indenter angle and contact conditions between the indenter and workpiece material – on the load-displacement characteristics are studied. The obtained results show an anisotropic nature of surface topography around the obtained indents.

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9

Rice, P. M., and R. E. Stoller. "An Application of a Method for Correlating Mechanical Property Changes with Microstructural Changes in Ion-Irradiated Specimens." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 1018–19. http://dx.doi.org/10.1017/s042482010016755x.

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A method for correlating mechanical property changes and microstructural changes as a function of depth in ion irradiated specimens has been applied to a series of model pressure vessel steels. The technique employs nanoindentation with very small indent depths, on cross sectional specimens, to measure changes in hardness with sub-micron spatial resolution. Conventional TEM imaging of the cross sectional specimens allows the investigation of the defect microstructure as a function of depth below the original irradiated surface. For ion irradiations (implantations) the dose varies as a function of depth in the specimen and can be calculated with reasonable accuracy using TRIM calculations. Thus changes in both hardness and defect microstructure can be measured and correlated, over a range of doses, from a single specimen.The technique has been applied to a set of model ferritic pressure vessel alloys to study the effect of various solutes on embrittlement. 2.5 MeV He ion irradiation was used to produce qualitatively similar microstructural features to those created in a nuclear reactor environment allowing the study to be carried out without the added complications associated with radioactive specimens. Figure la is an SEM image showing a set of nano-indents that starts on the left, beyond the end of range of the ions which is easily seen as the dark band. The indents eventually cross the thin oxide that marks the original irradiated surface (the white line) and enter the Fe electroplating seen here as the fine grained material at the bottom of the images. Figure lb is a higher magnification SEM image of the same indents showing the three-sided pyramid shaped indents reflective of the Berkovich diamond used in nanoindenting. Each of these residual indents is the result of a multipule indent process. The first indent is 50nm deep to acquire the sub-micron resolution hardness data, and the second is twice as deep (thus twice as wide) to clearly mark the position of the shallower indent before moving to the next position. Figure 2a is a bright-field TEM micrograph showing the defect microstructure of the entire irradiated region of an Fe + low N alloy, taken with g = {330} such that the dislocation loops appear dark. Figure 2b is a plot of the actual change in hardness, AH, as a function of depth below the original irradiated surface at the same scale, and for the same alloy shown in figure 2a.

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10

Kaboli, Shirin, Dina Goldbaum, Richard R. Chromik, and Raynald Gauvin. "Electron Channeling Contrast Imaging of Plastic Deformation Induced by Indentation in Polycrystalline Nickel." Microscopy and Microanalysis 19, no. 6 (October 11, 2013): 1620–31. http://dx.doi.org/10.1017/s1431927613013469.

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AbstractVickers microindentation and Berkovich nanoindentation tests were carried out on a polycrystalline nickel (Ni) bulk specimen. Electron channeling contrast imaging (ECCI) in conjunction with electron backscattered diffraction was used to image and characterize plastic deformation inside and around the indents using a field emission scanning electron microscope. The ECCI was performed with a 5 keV beam energy and 0° tilt specimen position. The strain field distribution, slip lines, and Taylor lattices were imaged on an indented surface. Orientation mapping was used to investigate the local crystallographic misorientation and identify specific ⟨110⟩ slip systems. An ion milling surface preparation technique was used to remove materials from the surface which permitted the study of deformed microstructure below the indent. A dislocation density of 1011 cm−2 was calculated based on the curvature of bend contours observed in the ECCI micrographs obtained from the Vickers indents. A yield strength of 500 MPa was calculated based on the size of the strain field measured from the ECCI micrographs of the nanoindents. The combination of ion milling, ECCI, and electron backscattered diffraction was shown to be beneficial to investigate the indentation-induced plastic deformation in a polycrystalline Ni bulk specimen.

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11

Li, H., and A. H. W. Ngan. "Size effects of nanoindentation creep." Journal of Materials Research 19, no. 2 (February 2004): 513–22. http://dx.doi.org/10.1557/jmr.2004.19.2.513.

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The size effects on indentation creep were studied on single-crystal Ni3Al, polycrystalline pure Al, and fused quartz samples at room temperature. The stress exponents were measured by monitoring the displacement during constant indentation loads after correction for thermal drift effects. The stress exponents were found to exhibit a very strong size effect. In the two metals Al and Ni3Al, the stress exponent for very small indents is very small, and for Al, this even approaches unity, suggesting that linear diffusional flow may be the controlling mechanism. The stress exponents in these two metals rise rapidly to over 100 as the indent size gets larger, indicating a rapid change of the dominating mechanism to climb-controlled to eventually glide-controlled events. In fused quartz, the stress exponent also exhibits a sharply rising trend as the indent size increases. The stress exponent is also close to unity at the smallest indents studied, and it rises rapidly to a few tens as the indent size gets larger.

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12

Wittge, J., A. Danilewsky, D. Allen, P. McNally, Z. J. Li, T. Baumbach, E. Gorostegui-Colinas, et al. "X-ray diffraction imaging of dislocation generation related to microcracks in Si wafers." Powder Diffraction 25, no. 2 (June 2010): 99–103. http://dx.doi.org/10.1154/1.3392369.

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The nucleation of dislocations at indents in silicon following rapid thermal annealing (RTA) has been examined by X-ray diffraction imaging (topography). For indentation loads below 200 mN, no slip bands were generated from the indent sites following RTA at 1000 °C under spike conditions. Upon plateau annealing at 1000 °C, slip dislocations were propagated from some indents but not all. Slip was also observed from edge defects not associated with indentation. For 500-mN indentation load, large scale dislocation sources were generated from the indent sites propagating on two of the four {111} slip planes. These dislocations multiplied into macroscopic-scale slip bands. A significant change in morphology was observed in the 60° dislocation segments after the screw segment reached the rear surface of the wafer. Dislocations changed line direction and in some cases appeared to leave the Peierls trough during glide.

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13

Kim, Chang-Hoon, and Arthur H. Heuer. "A high-temperature displacement-sensitive indenter for studying mechanical properties of thermal barrier coatings." Journal of Materials Research 19, no. 1 (January 2004): 351–56. http://dx.doi.org/10.1557/jmr.2004.19.1.351.

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Electron beam physical-vapor-deposited Y2O3-stabilized ZrO2 thermal barrier coating (TBC) samples were indented from room temperature to 900 °C using an instrumented high-temperature vacuum displacement-sensitive indenter. Hardness and elastic modulus were determined from the load–displacement curves recorded during indentation. Both the hardness and the elastic modulus of the TBCs were much lower than those of dense ceramics of a similar composition; this is attributed to the increased compliance that results from the porous columnar microstructure of the TBCs. In addition, the TBCs showed an unusual absence of elastic recovery at the residual indents compared to the dense ceramics.

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Michalikova, Jana, Štefan Michalik, Jozef Bednarcik, Pavol Hvizdos, Matthias Alfeld, and Hermann Franz. "Strain Mapping of Indented Zr-Based Bulk Metallic Glass Using Nano-Diffraction." Key Engineering Materials 662 (September 2015): 51–54. http://dx.doi.org/10.4028/www.scientific.net/kem.662.51.

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The state-of-the-art nano-diffraction technique available at the P06 beamline of the synchrotron radiation source PETRA III was used to observe the strain distribution induced within bulk metallic glass by nano-indentation. Bulk metallic glass (BMG) with nominal composition Zr52.5Ti5Cu17.9Ni14.6Al10 at.% was prepared by conventional copper mold injection casting. Using the Berkovich indenter a series of indents forming a line was introduced on to the polished surface of the BMG sample. It has been shown that spatially resolved matrix scans with a nanometer sized beam (600 × 600 nm2) can identify positions of the indents and quantitatively describe the strain state after nano-indentation.

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LEE, YUN-HEE, JONG SEO PARK, HAE MOO LEE, and SEUNG HOON NAHM. "STRESS-STRAIN RELATIONSHIP OF ZR55AL10NI5CU30 METALLIC GLASS ANALYZED BY 3D IMAGES ON SPHERICAL INDENTS." International Journal of Modern Physics B 24, no. 15n16 (June 30, 2010): 2453–58. http://dx.doi.org/10.1142/s0217979210065088.

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Mechanically polished surface of Zr 55 Al 10 Ni 5 Cu 30 metallic glass was indented with a rigid ball 0.5 mm in diameter and its corresponding load-depth curve was recorded automatically. Although a stress-strain relationship beneath the indenter can be analyzed from the raw indentation curve, the current analysis developed for crystalline solids can mislead erroneous properties because it does not consider significant material pile-ups in amorphous metallic glasses. Thus, we proposed a novel indent image processing technique for characterizing the contact and flow properties in the metallic glasses; the contact area was measured by differentiating a three-dimensional indent morphology digitized by a surface profiler and a surface-stretching strain was newly defined in order to estimate the flow properties. Finally, the work-hardening index estimated was about 0.05, comparable with the typical value measured from uniaxial compression in the Zr -based metallic glass.

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Zhang, Yijun, Yang-Tse Cheng, and David S. Grummon. "Understanding indentation-induced two-way shape memory effect." Journal of Materials Research 22, no. 10 (October 2007): 2851–55. http://dx.doi.org/10.1557/jmr.2007.0356.

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Spherical indents in NiTi shape memory alloys can have reversible depth change: deeper depth in the martensitic phase at low temperature and shallower depth in the austenitic phase at high temperature. This is the indentation-induced two-way shape memory effect. After polishing the indents, two-way reversible surface protrusions can occur on the shape memory alloy surfaces upon heating and cooling. The height of the surface protrusion is about the same as the depth of the reversible indent. Further polishing reduces the height of the surface protrusion, which disappears completely when the polished depth is about the length of the contact radius. By comparing finite element analysis and experimental data, we show that the depth at which a protrusion disappears is close to the 10% strain boundary. This suggests that slip-plasticity is responsible for the observed indentation-induced two-way shape memory effect.

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17

King, William P., and Kenneth E. Goodson. "Thermomechanical Formation of Nanoscale Polymer Indents With a Heated Silicon Tip." Journal of Heat Transfer 129, no. 11 (January 15, 2007): 1600–1604. http://dx.doi.org/10.1115/1.2764088.

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In thermomechanical data storage, a heated atomic force microscope cantilever tip is in contact with and scans over a polymer film. Heating in the cantilever and cantilever tip induces local deformation of the polymer near the tip, with indents as small as 22nm. This paper reports a simple modeling approach for predicting heat and mass transfer in the cantilever tip and polymer with the goal of predicting indent formation conditions. The model accounts for subcontinuum conduction in the cantilever tip and for the time- and temperature-dependent mechanical properties of the polymer. Simulations predict steady state and transient indent formation, and the results compare well with data. For loading forces 30–200nN and a tip radius of 20nm, a cantilever temperature of 200°C is required to form an indent at steady state. For heating pulses as short as 5μs, the cantilever temperature required for bit formation is as high as 500°C. By quantifying the conditions required for indent formation, this work may improve the operation of heated probes for thermomechanical data storage.

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Zhao, Yang, Fan Sun, Peng Jiang, and Yongle Sun. "Effects of Roughness on Stresses in an Oxide Scale Formed on a Superalloy Substrate." Coatings 11, no. 4 (April 19, 2021): 479. http://dx.doi.org/10.3390/coatings11040479.

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The effects of surface roughness on the stresses in an alumina scale formed on a Fecralloy substrate are investigated. Spherical indenters were used to create indents with different radii and depths to represent surface roughness and then the roughness effect was studied comprehensively. It was found that the residual stresses in the alumina scale formed around the rough surface are almost constant and they are dominated by the curvature rather than the depth of the roughness. Oxidation changes the surface roughness. The edge of the indent was sharpened after oxidation and the residual stress there was released presumably due to cracking. The residual stresses in the alumina scale decrease with increase in oxidation time, while the substrate thickness has little effect, given that the substrate is thicker than the alumina scale. Furthermore, the effect of roughness on the oxide growth stress is analysed. This work indicates that the surface roughness should be considered for evaluation of stresses in coatings.

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19

Pharr, G. M., W. C. Oliver, and D. S. Harding. "New evidence for a pressure-induced phase transformation during the indentation of silicon." Journal of Materials Research 6, no. 6 (June 1991): 1129–30. http://dx.doi.org/10.1557/jmr.1991.1129.

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Scanning electron micrographs of indents in (111) silicon reveal that a thin layer of material immediately adjacent to the indenter is plastically extruded. The fact that the material can be deformed in this way indicates that it has metallic-like mechanical properties. This is presented as new evidence that a pressure-induced phase transformation to the metallic state occurs during the indentation of silicon.

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Pajares, A., F. Guiberteau, R. W. Steinbrech, and A. Dominguez-Rodriguez. "Residual stresses around Vickers indents." Acta Metallurgica et Materialia 43, no. 10 (October 1995): 3649–59. http://dx.doi.org/10.1016/0956-7151(95)90148-5.

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Salman, S., S. Sugiman, E. D. Sulistyawati, A. Zainuri, and R. Robiansyah. "Analisa pengaruh jumlah indentasi dan distribusi tegangan geser pada sambungan perekat baja-baja (paper ini telah dicabut)." Dinamika Teknik Mesin 9, no. 2 (July 1, 2019): 95. http://dx.doi.org/10.29303/dtm.v9i2.282.

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Adhesive joints are widely used in automotive industry and shipping industry. Efforts to increase the strength of the connection are still underway. This study aims to determine the effect of the amount of indentation on shear strength on low carbon steel joints and the failure mode when the number of indents is different. The connection was made of low carbon steel with epoxy adhesive as adhesive and adhesive thickness of 0.3 mm. The number of indents varied; with and without indentations 4, 9, 16, and 25 respectively. The indentation process was made by using pillar drilling with 1.5 mm diameter of drill bit. From the results, the specimen without indentation had highest shear strength was about 22 MPa. Connection strength tended to decrease with increasing indentation. By finite element modeling, the distribution of shear stress tended to be uniform without indentation, and the stress at the end of the connection for indented connections was higher than without indentation.

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Savić, Adrijana, Aref Shafiei Dastgerdi, Robert J. Peterman, and B. Terry Beck. "The Influence of Wire Type Indentation on Longitudinal Splitting in Pre-Stressed Concrete." Advanced Materials Research 1165 (July 23, 2021): 65–86. http://dx.doi.org/10.4028/www.scientific.net/amr.1165.65.

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The important characteristic in the creation of longitudinal splitting cracks in pretensioned concrete members has found to be the geometry of the pre-stressing wire indents. Longitudinal splitting along prestressing tendons can result in severe splitting of prestressed member in the field under loading over time. The research evaluated the influence of wire type indentation on the longitudinal splitting in prestressed concrete members fabricated with different concrete mixtures and different compressive strength of concrete. A key objective was to find the best type of wire to avoid failures in the field. A study was conducted at Kansas State University to understand the effect of wire type on the longitudinal splitting between prestressing steel and prestressed concrete. Three different types of wires will be presented in this paper denoted as “WB”, “WF” and “WQ”. The wires have different parameters which include indent depth, indent width, indent sidewall angle, indent pitch and indent volume.

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Burik, Peter, and Ladislav Pešek. "Effect of Experimental Factors on Hardness Measurement Using the UCI Technique." Materials Science Forum 782 (April 2014): 61–64. http://dx.doi.org/10.4028/www.scientific.net/msf.782.61.

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The work experimentally analyses the effect of various factors on hardness measured values on thin steel sheets using Ultrasonic Contact Impedance (UCI) technique. The conditions experimentally used are compared with that according the ASTM A 1038-08 standard. UCI is an experimental technique for indirect hardness measurement. The equipment uses a Vickers indenter and the hardness measurement is based on the change of the resonance frequency during indenter ́s penetration [.The UCI hardness may depend on some factors, therefore optimal measurement conditions must be determined. The effect of distance between indents, zinc coating, sample weight, sample mounting and adhesive material for sample fixation were determined.

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Lloyd, S. J., A. Castellero, F. Giuliani, Y. Long, K. K. McLaughlin, J. M. Molina-Aldareguia, N. A. Stelmashenko, L. J. Vandeperre, and W. J. Clegg. "Observations of nanoindents via cross-sectional transmission electron microscopy: a survey of deformation mechanisms." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 461, no. 2060 (June 24, 2005): 2521–43. http://dx.doi.org/10.1098/rspa.2005.1470.

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Examination of cross-sections of nanoindents with the transmission electron microscope has recently become feasible owing to the development of focused ion beam milling of site-specific electron transparent foils. Here, we discuss the development of this technique for the examination of nanoindents and survey the deformation behaviour in a range of single crystal materials with differing resistances to dislocation flow. The principal deformation modes we discuss, in addition to dislocation flow, are phase transformation (silicon and germanium), twinning (gallium arsenide and germanium at 400 °C), lattice rotations (spinel), shear (spinel), lattice rotations (copper) and lattice rotations and densification (TiN/NbN multilayers). The magnitude of the lattice rotation, about the normal to the foil, was measured at different positions under the indents. Indents in a partially recrystallized metallic glass Mg 66 Ni 20 Nd 14 were also examined. In this case a low-density porous region was formed at the indent tip and evidence of shear bands was also found. Further understanding of indentation deformation will be possible with three-dimensional characterization coupled with modelling which takes account of the variety of competing deformation mechanisms that can occur in addition to dislocation glide. Mapping the lattice rotations will be a particularly useful way to evaluate models of the deformation process.

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Lim, Y. Y., M. M. Chaudhri, and Y. Enomoto. "Accurate determination of the mechanical properties of thin aluminum films deposited on sapphire flats using nanoindentations." Journal of Materials Research 14, no. 6 (June 1999): 2314–27. http://dx.doi.org/10.1557/jmr.1999.0308.

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Nanoindentations using a Berkovich diamond indenter have been made on 1, 2, and 5 μm thick 99.99% purity polycrystalline aluminum films thermally evaporated in vacuum on to 2 mm thick R-cut polished sapphire flats. The projected contact areas of the residual indentations were estimated from the unloading load-displacement curves, and some of the indentations were imaged with an atomic force microscope (AFM). It was found that a large majority of indents showed material pileup, and the projected areas of these indents, as measured with the AFM, were up to 50% greater than those calculated from the unloading curves. This discrepancy between the calculated and directly measured indentation areas has a strong influence on the derived values of Young's modulus and hardness of the aluminum films. Using a new analytical model, Young's modulus of the aluminum films has been determined to be in the range of 50–70 GPa, independent of the relative indentation depth. The composite nanohardness of the 1 and 2 μm thick films was found to have a load-independent value of 1 GPa, whereas the composite nanohardness of the 5 μm film decreased from 1 to 0.7 Gpa with increasing indenter penetration. Finally, it has been suggested that in order to improve the accuracy with which the mechanical properties of thin films or bulk specimens can be determined by nanoindentation techniques, the projected contact areas should be measured by direct methods, such as atomic force microscopy.

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V.Prashanth, K., A. Tejasri, K. Sandeep, U. Sateesh Kumar, and G. Swarupa. "Design of UWB Antenna with WLAN & X-Band Notch for Wireless Communication." International Journal of Engineering & Technology 7, no. 2.7 (March 18, 2018): 484. http://dx.doi.org/10.14419/ijet.v7i2.7.10868.

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In this proposition, a traditional UWB antenna with twofold indent channels was intended for a few remote applications. The exhibited antenna is outlined having estimations of 30 × 35 × 1.6 mm3 with a fix of rectangular staircase design. The dismissal bands are WLAN at 5 GHz (5.1 - 5.8 GHz) and the satellite X-band from space to earth (7.25 - 7.75 GHz). The patch with a step design with a modified π-formed opening gets the ultra-wide band. The UWB scope of 3.1 - 10.6 GHz affirmed by FCC can possibly cause interferences in the various wireless systems applications.. With a specific end goal to lessen these interferences, we settled on the band indent. In this proposed outline, the WLAN has scores setting a U-molded opening in the patch and the X-band has indents with a reversed T-shape in the ground plane.

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Hansen, Lars N., Emmanuel C. David, Nicolas Brantut, and David Wallis. "Insight into the microphysics of antigorite deformation from spherical nanoindentation." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2165 (January 6, 2020): 20190197. http://dx.doi.org/10.1098/rsta.2019.0197.

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The mechanical behaviour of antigorite strongly influences the strength and deformation of the subduction interface. Although there is microstructural evidence elucidating the nature of brittle deformation at low pressures, there is often conflicting evidence regarding the potential for plastic deformation in the ductile regime at higher pressures. Here, we present a series of spherical nanoindentation experiments on aggregates of natural antigorite. These experiments effectively investigate the single-crystal mechanical behaviour because the volume of deformed material is significantly smaller than the grain size. Individual indents reveal elastic loading followed by yield and strain hardening. The magnitude of the yield stress is a function of crystal orientation, with lower values associated with indents parallel to the basal plane. Unloading paths reveal more strain recovery than expected for purely elastic unloading. The magnitude of inelastic strain recovery is highest for indents parallel to the basal plane. We also imposed indents with cyclical loading paths, and observed strain energy dissipation during unloading–loading cycles conducted up to a fixed maximum indentation load and depth. The magnitude of this dissipated strain energy was highest for indents parallel to the basal plane. Subsequent scanning electron microscopy revealed surface impressions accommodated by shear cracks and a general lack of dislocation-induced lattice misorientation. Based on these observations, we suggest that antigorite deformation at high pressures is dominated by sliding on shear cracks. We develop a microphysical model that is able to quantitatively explain Young’s modulus and dissipated strain energy data during cyclic loading experiments, based on either frictional or cohesive sliding of an array of cracks contained in the basal plane. This article is part of a discussion meeting issue ‘Serpentinite in the earth system’

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Lloyd, S. J., J. M. Molina-Aldareguia, and W. J. Clegg. "Deformation under nanoindents in Si, Ge, and GaAs examined through transmission electron microscopy." Journal of Materials Research 16, no. 12 (December 2001): 3347–50. http://dx.doi.org/10.1557/jmr.2001.0461.

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Cross sections through nanoindents on Si, Ge, and GaAs {001} were examined through transmission electron microscopy. A focused ion beam workstation was used to machine electron transparent windows through the indents. In both Si and Ge there was a transformed zone immediately under the indent composed of amorphous material and a mixture of face-centered-cubic and body-centered cubic crystals. Cracking and dislocation generation were also observed around the transformed zone. In GaAs the dominant deformation mechanism was twinning on the {11} planes. The hardness of these materials is discussed in light of these observations and their macroscopic material properties such as phase transformation pressure.

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Scurr, David J., and Stephen J. Eichhorn. "Analysis of local deformation in indented Ensis Siliqua mollusk shells using Raman spectroscopy." Journal of Materials Research 21, no. 12 (December 2006): 3099–108. http://dx.doi.org/10.1557/jmr.2006.0382.

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The local deformation surrounding an indented area of Ensis siliqua mollusk shell is characterized using a Raman spectroscopic technique, the findings of which are related to the material’s mechanical function. Microhardness indentation of four directional planes is used to show the marked anisotropy of the structure, where the outer and inner layers of the shell are found to have a significantly higher microhardness value of 4.82 ± 0.02 GPa, compared with transverse and longitudinal cross-sectional values of 3.00 ± 0.07 GPa. This difference is related to the crossed lamellar microstructure of the shell, which is oriented to provide the maximum resistance to external attack from predators. Nanoindentation of the material shows no such anisotropy, giving mean hardness and modulus values for the four directional planes of 3.86 ± 0.10 GPa and 82.4 ± 2.7 GPa respectively, thereby clarifying the prominent role of microstructure in such materials. Scanning electron microscopy of indented samples shows that plastic deformation and delamination occur to different extents, depending on the orientation of the structure and local microstructural features such as prismatic layers. A Raman spectroscopic technique has been used to map relative deformation in the vicinity of the indents, showing that the amount of plastic or permanent deformation can be quantified, and that material delamination can be distinguished from other forms of deformation such as local cracking. These experimental methods are repeated using samples of non-biogenic aragonite, which act as an analogous material for comparison with the shell. It is proposed that the analysis of microhardness indents using Raman spectroscopy could be applied to other biomaterials exhibiting anisotropy.

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Nagy, Péter, András Juhász, and Erika Kálmán. "AFM Investigation on Vickers Indents: An Artefact?" Microchimica Acta 132, no. 2-4 (April 2000): 457–60. http://dx.doi.org/10.1007/s006040050094.

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Jiang, Chulin, Michael Davis, and Jurgita Zekonyte. "Finding Minimal Optimal Indent Separation for Polystyrene via Instrumental Nanoindentation and FEA Method." Applied Sciences 10, no. 12 (June 22, 2020): 4262. http://dx.doi.org/10.3390/app10124262.

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Nanoindentation became a standard non-destructive technique to measure mechanical properties at the submicron scale of various materials. A set of empirical rules were established to guarantee the validity of the results. One of those rules is the separation between individual indents that should be 20–30 times maximum indentation depth. This paper investigates the influence of the distance between indents on the accuracy of mechanical properties for polystyrene with a view to determine minimum optimal separation that is needed to measure various material properties. A series of different depths with three different orientations was considered through both the experimental and finite element method to explore the relationship between the distance and indentation depth. Both methods demonstrated that hardness and modulus values for polystyrene keep stable with the distance approximately 15 times the maximum indentation depth for the matrix type set up, and nominal separation of 10 is enough when indents are executed in a single row or column.

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Hájková, Petra, and Aleš Jíra. "Micromechanical Analysis of Complex Structures by Nanoindentation." Key Engineering Materials 731 (March 2017): 60–65. http://dx.doi.org/10.4028/www.scientific.net/kem.731.60.

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Civil engineers like to use complex construction systems which resist mechanical strain well. Complex material and structural arrangement is possible to see in biological materials as wood but as bone or dentin too. This paper deals with a property trend of biological material, dentin, and can serve as an inspiration for designing resistant constructions. The analysis was carried out by a method of nanoindentation. The differences of property values depending on location of indents in dentin structure were surveyed. Especially, the differences of hardness and reduced modulus were important. The huge number of indents was made during the experiment. The indents were divided into categories according to the distance from the nearest material interface. The upward trend was found out for both observed properties. The category which was the closest to the material interface showed the average value of hardness ~ 965 MPa, whereas the furthest ~ 1222 MPa. It was growth more than 20%. Reduced modulus showed similar trend. These results are different from these which have been performed by other authors so far.

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Bruet, B. J. F., H. J. Qi, M. C. Boyce, R. Panas, K. Tai, L. Frick, and C. Ortiz. "Nanoscale Morphology and Indentation of Individual Nacre Tablets from the Gastropod Mollusc Trochus Niloticus." Journal of Materials Research 20, no. 9 (September 2005): 2400–2419. http://dx.doi.org/10.1557/jmr.2005.0273.

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The inner nacreous layer of gastropod mollusc Trochus niloticus is composed of ∼95 wt% planar arrays of polygonal aragonite-based tablets (∼8 μm wide, ∼0.9 μm thick, stacked ∼40 nm apart) and ∼5 wt% biomacromolecules. High-resolution tapping mode atomic force microscope images enabled nanoscale resolution of fractured tablet cross-sections, the organic component, and deformation of individual nanoasperities on top of tablet surfaces. Nanoindentation was performed on individual nacre tablets and the elastic modulus E and yield stress σy were reduced from elastic-plastic finite element simulations yielding E = 92 GPa, σy = 11 GPa (freshly cleaved samples) and E = 79 GPa, σy = 9 GPa (artificial seawater soaked samples). Images of the indents revealed extensive plastic deformation with a clear residual indent and surrounding pileup.

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Matsumoto, Mitsuhiro, Hirofumi Harada, Koichi Kakimoto, and Ji Wang Yan. "Study on Mechanical Properties of Single-Crystal Silicon Carbide by Nanoindentation." Advanced Materials Research 1136 (January 2016): 549–54. http://dx.doi.org/10.4028/www.scientific.net/amr.1136.549.

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In order to clarify the mechanical properties of single-crystal silicon carbide (SiC), nanoindentation was performed on a 4H-SiC wafer. The change of hardness with the angle between the wafer orientation flat and the indenter edge, the maximum load and the loading rate were investigated. The hardness reached maximum at an indentation load of 12 mN in the range of 3-50 mN. Hardness decreased under two conditions: when the edge of the indenter tip is parallel to the [11-20] direction, and when a very low loading rate was used. Transmission electron microscopy was used to observe dislocations and cracks under the indents. It was demonstrated that the deformation process of SiC involved three steps with respect to the increase of the indentation load. These results provide information for improving ductile machining process of single crystal SiC.

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Lilleodden, E. T., W. Bonin, J. Nelson, J. T. Wyrobek, and W. W. Gerberich. "In situ imaging of μN load indents into GaAs." Journal of Materials Research 10, no. 9 (September 1995): 2162–65. http://dx.doi.org/10.1557/jmr.1995.2162.

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Nanomechanical devices constitute an important and growing field, as they allow for new understanding of the mechanical properties at interfaces and surfaces. As an example, a newly developed nanoindentation device has been used to accomplish μN load indents into GaAs. First, it is shown that a plastic zone can be measured and is comparable to theory. Also, it is shown that the rate of indentation affects both the depth and upset zone of low load indents, implying a strain-rate sensitivity effect at room temperature. This is reinforced by observation of what appears to be a glide-based relaxation process.

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36

Lavanian, D. "COMPUTERISATION OF MEDICAL STORE INDENTS : A PILOT STUDY." Medical Journal Armed Forces India 50, no. 1 (January 1994): 74. http://dx.doi.org/10.1016/s0377-1237(17)31049-3.

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37

Jia, Yun-Fei, Yuan-Yuan Cui, Fu-Zhen Xuan, and Fuqian Yang. "Comparison between single loading–unloading indentation and continuous stiffness indentation." RSC Advances 7, no. 57 (2017): 35655–65. http://dx.doi.org/10.1039/c7ra06491h.

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Buršík, Jiří, Ivo Kuběna, Vilma Buršíková, Pavel Souček, Lukáš Zábranský, Saeed Mirzaei, and Petr Vašina. "W-B-C Nanostructured Layers - Microstructure and Mechanical Properties." Solid State Phenomena 258 (December 2016): 416–19. http://dx.doi.org/10.4028/www.scientific.net/ssp.258.416.

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Several W-B-C layers were prepared by magnetron sputtering. The microstructure of thin layers was observed by means of scanning and transmission electron microscopy on cross sections prepared using a focused ion beam. Both undisturbed layers and the volume under indentation prints were inspected. The W-B-C layers are fine nanostructured materials about 2 μm thick and indents with loads up to 1 N do not cause any visible defects (cracks, delamination etc). The results were correlated with mechanical properties characterized by means of nanoindentation experiments in both the static and the dynamic loading regime using a Berkovich indenter. Elastic modulus, indentation hardness and fracture resistance of prepared nanostructured coatings were evaluated and discussed.

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Haq, Ayesha J., P. R. Munroe, M. Hoffman, P. J. Martin, and A. Bendavid. "Berkovich indentation of diamondlike carbon coatings on silicon substrates." Journal of Materials Research 23, no. 7 (July 2008): 1862–69. http://dx.doi.org/10.1557/jmr.2008.0232.

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The deformation behavior of diamondlike carbon (DLC) coatings on silicon substrates induced by Berkovich indentation has been investigated. DLC coatings deposited by a plasma-assisted chemical vapor deposition technique were subjected to nanoindentation with a Berkovich indenter over a range of maximum loads from 100 to 300 mN. Distinct pop-ins were observed for loads greater than 150 mN. However, no pop-out was observed for the loads studied. The top surface of the indents showed annular cracks with associated fragmented material. The cross sections showed up to 20% localized reduction in thickness of the DLC coating beneath the indenter tip. Cracking, {111} slip, stacking faults, and localized phase transformations were observed in the silicon substrate. The discontinuities in the load–displacement curves at low loads are attributed to plastic deformation of the silicon substrate, whereas at higher loads they are attributed to plastic deformation as well as phase transformation.

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Surowiec, M. R., and B. K. Tanner. "X-ray topographic study of dislocation around indents on {111} surfaces of indium antimonide." Journal of Applied Crystallography 20, no. 6 (December 1, 1987): 499–504. http://dx.doi.org/10.1107/s002188988708614x.

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The dislocation configurations around microindentations on {111} surfaces of InSb have been studied by transmission X-ray topography. In all cases, glide on the B-type {111} planes only occurs. The most extended dislocation loops occur around A-surface indents. Glide occurs on inclined {111} planes and the loops have extended screw segments parallel to the surface. Around B-surface indents dislocations glide predominantly on the ({\bar 1} {\bar 1} {\bar 1}) plane parallel to the surface. The mobility of these dislocations is about two or three times less than the former type. Direct evidence for the formation of edge dislocation barriers from reactions between dislocations gliding in the ({\bar 1} {\bar 1} {\bar 1}) plane is presented.

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41

Achiriloaiei, Daniel, Cristian Sorin Nes, Ion Dumitru, and Anghel Cernescu. "On the Influence of the Contact Force and the Angle between the Wires on ACSR Conductors’ Mechanical Properties and Durability." Key Engineering Materials 665 (September 2015): 33–36. http://dx.doi.org/10.4028/www.scientific.net/kem.665.33.

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Aluminium clad steel reinforced cables are widely used in long distance electrical energy transport. Under the influence of weather conditions, the conductors are subjected to additional stress, which may lead to accelerated deterioration and premature breakage. This phenomenon depends much on contact mechanics. Due to the rough geometry of real mechanical surfaces, the elastic-plastic contact between bodies occurs at several points simultaneously. The contact between wires or between the wires and the suspension clamp, which is regarded as a critical location, changes the mechanical properties of the conductor with the emergence and development of contact indents. In order to understand the development of the indents ant their influence in the properties of the wires, indentation, tensile and fatigue tests were performed on wires taken from a steel-aluminium conductor. The problem of normal contact when plastic deformations are much higher than the elastic ones is extremely complex. The convex profile of the wires brings additional complications. Specific strain intensity is proportional to the depth of penetration. Experimental researches have shown that the shape and size of the indents occurred at the contact points have a significant influence on the tensile strength and lifetime of the conductors and local deformations determine certain features of fatigue crack initiation and propagation.

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42

Joslin, D. L., and W. C. Oliver. "A new method for analyzing data from continuous depth-sensing microindentation tests." Journal of Materials Research 5, no. 1 (January 1990): 123–26. http://dx.doi.org/10.1557/jmr.1990.0123.

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A new parameter, hardness/modulus2 (H/E2), has been derived from the equations used to calculate the hardness and elastic modulus from data taken during continuous depth-sensing microindentation tests. This paper discusses the use of this parameter to treat the data obtained from a sample whose surface roughness was of the same scale as the size of the indents. The resulting data were widely scattered. This scatter was reduced when the data were plotted in terms of H/E2 versus stiffness. The effect of surface roughness on the hardness and elastic modulus results is removed via stiffness measurements, provided single contacts are made between the indenter and the specimen. The function relating the cross-sectional area of the indenter versus the distance from its point is not required for calculation of H/E2, but the hardness and modulus cannot be determined separately. The parameter H/E2 indicates resistance to plastic penetration in this case.

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Lee, Yun Hee, Yong Hak Huh, Ju Young Kim, Seung Hoon Nahm, Jae Il Jang, and Dong Il Kwon. "Yield Property Characterization for Au and TiN Thin Films by Applying Nanoindentation Technique." Key Engineering Materials 326-328 (December 2006): 215–18. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.215.

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We tried to apply the nanoindentation technique to yield strength characterization by modifying a previous research. Although the yield strength determining technique developed by Kramer et al. has been successfully demonstrated for large scale indentations on bulky metals, its applicability is still doubtful to nanoscale indentations on thin films with severe roughness, anisotropy, and interfacial constraint. In order to overcome these problems, we combined the nanoindentation technique with a three-dimensional indent visualization technique in this study. Nanoindentation tests were performed for Au and TiN thin films and their corresponding indents were scanned by using an atomic force microscope. From the three-dimensional pile-up morphology, a circular pile-up boundary was measured and input into the yield strength formulation as an effective yielded zone radius. The yield strengths calculated were directly compared with those from the microtensile test.

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Choi, S. R., and J. A. Salem. "Interaction of cracks between two adjacent indents in glass." Journal of Materials Science 28, no. 2 (1993): 501–5. http://dx.doi.org/10.1007/bf00357830.

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Kim, Jong-Il, Yong-Hak Huh, and Yong-Hwan Kim. "Static Residual Tensile Strength Response of GFRP Composite Laminates Subjected to Low-Velocity Impact." Applied Sciences 10, no. 16 (August 7, 2020): 5480. http://dx.doi.org/10.3390/app10165480.

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The dependency of the static residual tensile strength for the Glass Fiber-Reinforced Plastic (GFRP) laminates after impact on the impact energy level and indent shape is investigated. In this study, two different laminates, unidirectional, [0°2]s) and TRI (tri-axial, (±45°/0°)2]s), were prepared using the vacuum infusion method, and an impact indent on the respective laminates was created at different energy levels with pyramidal and hemispherical impactors. Impact damage patterns, such as matrix cracking, delamination, debonding and fiber breakage, could be observed on the GFRP laminates by a scanning electron microscope (SEM), and it is found that those were dependent on the impactor head shape and laminate structure. Residual in-plane tensile strength of the impacted laminates was measured and the reduction of the strength is found to be dependent upon the impact damage patterns. Furthermore, in this study, stress concentrations in the vicinity of the indents were determined from full-field stress distribution obtained by three-dimensional Digital Image Correlation (3D DIC) measurement. It was found that the stress concentration was associated with the reduction of the residual strength for the GFRP laminates.

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Lecomte, J. S., L. T. Nguyen, F. Abbès, C. Schuman, and J. M. Raulot. "Contribution of the Nanoindentation to the Study of HCP Metals." Materials Science Forum 783-786 (May 2014): 2327–32. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2327.

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This study combines nanoindentation experiments, electron backscatter diffraction (EBSD) and atomic force microscopy (AFM) topographic measurements to investigate the material anisotropy contribution to the indentation behaviour of individual grains of various hexagonal-close packed (HCP) polycrystals with different axial ratio (zinc, magnesium and titanium). The grain size was much larger than the indents size to ensure quasi-single-crystal indentation and when, combined with an EBSD mapping, a wide variety of crystal orientations can be probed, which provides mechanical characterization of materials at the micro/nanoscale. Experimental curves can be used to determine the mechanical properties of the indented material. Furthermore, by using data issued from AFM topographic measurements, one can analyze the dislocations arrangements below and around the indentation print, and thus characterize the most probably activated deformation systems.

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47

Shi, Jingyu, D. L. S. McElwain, and S. A. Domanti. "Some Plastic Deformation Modes for Indentation of Half Space by a Rigid Body With Serrated Surface as a Model of Roughness Transfer in Metal Forming." Journal of Engineering Materials and Technology 124, no. 2 (March 26, 2002): 146–51. http://dx.doi.org/10.1115/1.1446864.

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This paper is concerned with the plastic deformation modes of the free surface of the half space between the teeth on the serrated surface of a rigid body. The rigid body indents the half space perpendicularly and the material of the half space is assumed to be elastic/rigid perfectly plastic. Plane-strain conditions are assumed. The emphasis in this paper is on the profile left on the surfaces of the material when the indentation proceeds to some depth and then the indenter is removed. Based on the observations from finite element results, slip line fields for the plastic deformation regions at various stages of indentation are proposed and the corresponding hodographs for the velocity field are presented. This has application in roughness transfer of final metal forming process.

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Allen, David, Jochen Wittge, Jennifer Stopford, Andreas Danilewsky, and Patrick McNally. "Three-dimensional X-ray diffraction imaging of process-induced dislocation loops in silicon." Journal of Applied Crystallography 44, no. 3 (May 6, 2011): 526–31. http://dx.doi.org/10.1107/s0021889811013264.

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In the semiconductor industry, wafer handling introduces micro-cracks at the wafer edge and the causal relationship of these cracks to wafer breakage is a difficult task. By way of understanding the wafer breakage process, a series of nano-indents were introduced both into 20 × 20 mm (100) wafer pieces and into whole wafers as a means of introducing controlled strain. Visualization of the three-dimensional structure of crystal defects has been demonstrated. The silicon samples were then treated by various thermal anneal processes to initiate the formation of dislocation loops around the indents. This article reports the three-dimensional X-ray diffraction imaging and visualization of the structure of these dislocations. A series of X-ray section topographs of both the indents and the dislocation loops were taken at the ANKA Synchrotron, Karlsruhe, Germany. The topographs were recorded on a CCD system combined with a high-resolution scintillator crystal and were measured by repeated cycles of exposure and sample translation along a direction perpendicular to the beam. The resulting images were then rendered into three dimensions utilizing open-source three-dimensional medical tomography algorithms that show the dislocation loops formed. Furthermore this technique allows for the production of a video (avi) file showing the rotation of the rendered topographs around any defined axis. The software also has the capability of splitting the image along a segmentation line and viewing the internal structure of the strain fields.

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Huu Hung, Nguyen, Pal Jen Wei, and Jen Fin Lin. "Compensating for Creep Effects in One-Indent Nanoindentation Tests." Applied Mechanics and Materials 764-765 (May 2015): 28–31. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.28.

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Detailed observations of nanoindentation static creep effects exhibited in polymethylmethacrylate (PMMA) is presented and discussed in this study. One-indent nanoindentation technique, the partial unloading measurement (PUM) method, is compared with the basic measurement BM method (i.e., an array of multiple single indents with various magnitudes). The experimental results for PMMA reveal a strong dependence on the loading conditions. It was found that the PUM results for PMMA are not consistent with the corresponding BM results due to significant static. The creep depths accumulated and increased the indentation depth, and thus the contact area. The hardness and elastic modulus evaluated from these experimental results decreased with the indentation depth (or load).The effect of static creep exhibited in polymers for the PUM method during the determination of mechanical properties was studied. A significant static creep effect was found for polymers when the indentation load was held in order to attenuate the rapid direction change between the loading and unloading segments.

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Pharr, G. M., and W. C. Oliver. "Nanoindentation of silver-relations between hardness and dislocation structure." Journal of Materials Research 4, no. 1 (February 1989): 94–101. http://dx.doi.org/10.1557/jmr.1989.0094.

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The depth dependence of hardness in a well-annealed single crystal of silver has been characterized in nanoindentation experiments. The work is based on similar experiments performed by Chen and Hendrickson, but extends their results to indent depths on the nanometer scale. The hardness is generally found to increase with decreasing depth, with a rather sharp increase observed at depths of less than 50 nm. Using etch pitting to reveal the surface dislocation structure after indentation, the sharp rise in hardness is found to be associated with the disappearance of dislocation rosette patterns and any signs of near-surface dislocation activity, thereby suggesting that very small scale indentation plasticity may take place by nondislocation mechanisms. However, order of magnitude calculations show that possible alternatives, specifically, diffusional mechanisms, are too slow to make significant contributions. It is suggested that for very small indents, either the surface dislocation debris is quickly annealed out before it can be observed or indentation plasticity is accommodated entirely by subsurface dislocation activity.

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Journal articles on the topic 'Indents'

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