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Dissertations / Theses on the topic 'Metallurgy and Material Science'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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1

Liu, Tong. "Construction of Supramolecular Structures by Mimicking Metallurgy." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron160370390740064.

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2

Lagerstedt, Anders. "On the shrinkage of metals and its effect in solidification processing." Doctoral thesis, KTH, Materials Science and Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-75.

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The shrinkage during solidification of aluminium and iron based alloys has been studied experimentally and theoretically. The determined shrinkage behaviour has been used in theoretical evaluation of shrinkage related phenomena during solidification.

Air gap formation was experimentally studied in cylindrical moulds. Aluminium based alloys were cast in a cast iron mould while iron based alloys were cast in a water-cooled copper mould. Displacements and temperatures were measured throughout the solidification process. The modelling work shows that the effect of vacancy incorporation during the solidification has to be taken into account in order to accurately describe the shrinkage.

Crack formation was studied during continuous casting of steel. A model for prediction of crack locations has been developed and extended to consider non-equilibrium solidification. The model demonstrates that the shrinkage due to vacancy condensation is an important parameter to regard when predicting crack formation.

The centreline segregation was studied, where the contributions from thermal and solidification shrinkage were analysed theoretically and compared with experimental findings. In order to compare macrosegregation in continuous casting and ingot casting, ingots cast with the same steel grade was analysed. However, the macrosegregation due to A-segregation is driven by the density difference due to segregation. This is also analysed experimentally as well as theoretically.

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3

Williams, Katherine E. (Katherine Edith). "An examination of Maya metallurgy, 1150 to 1544 A.D." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/32576.

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4

Bezur, Aniko. "Variability in Sican copper alloy artifacts: Its relation to material flow patterns during the Middle Sican Period in Peru, AD 900-1100." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280255.

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The Middle Sican culture, centered in the Lambayeque region on the north coast of Peru, began successful, intensive production of arsenical copper starting around AD 900. The excavation and analysis of Middle Sican burials has revealed that artifacts made of copper-arsenic alloys played an important role in mortuary practices and ritual activities. Copper-arsenic alloy artifacts were accessible to a relatively wide cross-section of the population, though in different amounts and forms. So-called grouped artifacts, for example, have primarily been recovered from elite graves and ritual contexts. Such grouped artifacts occurred in hoards and were organized into groups by wrapping with spun yarn, vegetable fibers, and textiles. This dissertation documents the patterning of compositional and morphological variation among three types of grouped copper artifacts and builds connections between the observed patterning and material flow during production and distribution in order to explore relations among producers and consumers. Morphological homogeneity is explored in relation to the methods of manufacture involved in the production of different types of grouped artifacts as well as the number of production units whose output was pooled to form a cache. Compositional standardization is addressed in relation to the mass of an individual object as well as material flow between smelting and smithing stages of the metallurgical chaine operatoire. Hypotheses are anchored in research on the production organization of other Middle Sican crafts as well as literature discussing connections between artifact variability and production organization.
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5

Cinkilic, Emre. "Alloy Design and Precipitation Modeling of High Fe Concentration Recycled Cast Aluminum Alloys for Structural Applications." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555599698005398.

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6

Seifi, Seyed Mohsen. "Mechanical Property Evolution and Thermal Remediation of Aluminum Magnesium 5xxx Alloys Following Low and Intermediate Temperature Thermal Exposure." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1365507691.

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7

Peterson, Benjamin Howard. "A Combinatorial Approach to the Development of a Creep Resistant Beta Titanium Alloy." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1218488816.

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8

Young, Adam Hamilton. "Study of the Nucleation Mechanism of a-Ti in Bimodal and Fully Lamellar Microstructures Developed in the High-Strength, Near-Beta Titanium Alloy, TIMETAL®18." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1374159274.

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9

Lawson, Benjamin James. "Compositional Optimization, Mechanical Properties, and Tempering Response in Type 410 Stainless Steel Welds." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1557201840078564.

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10

Johnson, Luke. "Solidification Cracking and Ductility-Dip Cracking Resistance of Ni-Base Filler Metal 52XL with Tantalum and Molybdenum Additions." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1575462956102374.

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11

Hultén, Leo, and Philip Jansson. "Investigation and Evaluation of Metal Powder Characterization Techniques : Currently available at the KTH Department of Material Science and Engineering." Thesis, KTH, Materialvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231469.

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The KTH Department of Materials Science and Engineering has lacked powder metallurgy research for many years, and as this field is constantly gaining in importance, such research needs to be reestablished. This requires the department to be able to accurately and efficiently characterize the properties of a powder, such as size distribution and composition, and in the short term, this needs to be done using non-specialized equipment. This project aimed to assess the availability and usefulness of both traditional and novel characterization methods by way of trial characterization experiments as well as a literature review.   The experiments resulted in some data about three sample powders, as well as the conclusions that size distribution could be effectively characterized by automatized image analysis, composition could be characterized using Energy Dispersive X-ray Spectroscopy and that sample preparation was key to good results. It was concluded that the department could conceivably evaluate the most important properties, but that sampling and sample preparation routines need to be established to ensure efficient characterization and representative data.
Materialinstitutionen på Kungliga Tekniska högskolan har i många år helt saknat pulvermetallurgiforskning och eftersom detta fält ständigt blir mer relevant behöver denna forskning återetableras. Detta kräver att institutionen med tillräcklig noggrannhet och effektivitet kan bestämma egenskaper hos ett pulver, såsom storleksfördelning och sammansättning, och på kort sikt behöver detta ske med ickespecialiserad utrustning. I detta projekt har tillgänglighet och användbarhet hos både traditionella och innovativa analysmetoder utvärderats med hjälp av experimentell karaktärisering av pulver samt en litteraturstudie. Experimenten gav data om de tre undersökta pulvren och resulterade även i slutsatsen att storleksfördelning kunde bestämmas med automatiserad bildanalys, att samansättning kunde bestämmas med Energi Dispersiv Röntgen Spektroskopi och att provpreparering äravgörande för bra resultat. Av detta följer att institutionen rimligtvis kan bestämma de viktigaste egenskaperna hos ett pulver, men att rutiner för provtagning och provpreparering behöver etableras för att säkerställa effektiv analys och representativ data.
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12

Wessman, Andrew E. "Physical Metallurgy of Rene 65, a Next-Generation Cast and Wrought Nickel Superalloy for use in Aero Engine Components." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1467126769.

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13

Demmons, Alan C. "Superalloy Metallurgy a Gleeble Study of Environmental Fracture in Inconel 601." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1595.

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At temperatures above 0.5 Tm and in aggressive atmospheres predicting alloy performance is particularly challenging. Nickel alloys used in regimes where microstructure and properties are altered dynamically present unique requirements. Exposure may alter properties with unexpected early failure. The Gleeble is a valuable tool for investigation and simulation of thermo-mechanical properties of an alloy in various regimes up to the threshold of melting. In this study, four regimes of temperature and strain rate were simulated in an argon atmosphere to both investigate and document normal and abnormal failure modes. Commercial Inconel 601 was tested in selected regimes and in two treatments (as received and strain aged). Next two exposed conditions (TEOS and Hydride) were tested. Slow strain-rate and high temperature produced brittle intergranular fracture. Exposure at elevated temperature to process gases reduced both strength and ductility in both TEOS and Hydride. TEOS exposure reduced reduction in area in the alloy significantly more than the Hydride exposure.
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14

Niezgoda, Stephen Richard Kalidindi Surya. "Stochastic representation of microstructure via higher-order statistics : theory and application /." Philadelphia, Pa. : Drexel University, 2010. http://hdl.handle.net/1860/3320.

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15

Chen, Ke. "The Origin of Coarse Grain Structure in Friction-Stir Welded AA5083 after Heat Treatment." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1244047069.

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16

Welk, Brian A. "Microstructural and Property Relationships in β-Titanium Alloy Ti-5553." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1262191957.

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17

May, Katelun. "Small Scale Tensile Testing of Titanium Alloys." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1282099780.

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18

Caron, Jeremy Leonard. "Weldability Evaluation of Naval Steels." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1285050450.

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19

Yu, Xinghua. "Multi-Scale Characterization of Heat-Affected Zone in Martensitic Steels." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1348081074.

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20

Zhong, Wei. "Measurement of Diffusion Coefficients of Nine Elements in Magnesium and Establishment of a Comprehensive Mobility Database for Lightweight Magnesium Alloys." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1557147025847122.

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21

Park, Conrad. "Mechanical Performance and Structure-Property Relations in6061B Aluminum Metal Matrix Composites." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1547842396716777.

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22

Cooney, Elizabeth Myers. "Bronze metallurgy in Iron Age central Europe : a metallurgical study of Early Iron Age bronzes from Stična, Slovenia." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39480.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (v. 2, p. 375-377).
The Early Iron Age (750-450 BCE) marks a time in the European Alpine Region in which cultural ideologies surrounding bronze objects and bronze production were changing. Iron was becoming the preferred material from which to make many utilitarian objects such as weapons and agricultural tools; this change can be clearly seen in the different treatments of bronze object deposits from the Late Bronze Age to the Early Iron Age. The Early Iron Age hillfort settlement of Sticna in what is now southeastern Slovenia was one of the first incipient commercial centers to take advantage of the new importance placed on iron, conducting trade with Italy, Greece, the Balkans, and northern Europe. This metallurgical study of bronze funerary objects from Sticna identifies construction techniques, use patterns, and bronze metallurgical technologies from the ancient region of Lower Carniola. This information is then used to explore the cultural importance of bronze at Early Iron Age Sticna and to compare the bronze work of Lower Carniola with that of other regions in central Europe and Italy from this time of great change in Iron Age Europe.
S.M.
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23

Semple, Jennifer K. Semple. "Pedigreed Material Property Data for Residual Stress and Distortion Modeling of Naval Steel Weldments." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1533813179740352.

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24

Muscat, Daniel. "Silicon nitridesilicon nitride whisker-reinforced composites." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60102.

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One of the major setbacks of ceramic materials is their inherent brittle nature which often leads to catastrophic failure, especially under impact and tensile stress conditions. Whisker-reinforcement of ceramic matrices has been shown to be an effective way of increasing toughness. However, the hot-pressing techniques being used at present are expensive. Si$ sb3$N$ sb4$ is a major contender for high temperature application, mainly due to its excellent mechanical, chemical and thermal properties.
In this work Si$ sb3$N$ sb4$ whiskers have been incorporated into a Si$ sb3$N$ sb4$ matrix and densified using pressureless sintering. An isotropic distribution of whiskers in the starting powder was seen to inhibit shrinkage of the bulk material as a result of whisker bridging.
An extrusion process was developed to align the whiskers such that they do not impinge on one another. This was done using a water soluble, cellulose based plasticizer. The process was sensitive to water content and mixing. Entrapped air caused problems in the extrudate, resulting in misaligned areas in the microstructure. Relative densities of 94.5% were obtained for composites having 15% whiskers. The toughness of this material was measured to be 13.5MPa.m$ sp{1/2}$ in the direction perpendicular to the direction of extrusion.
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25

Baczynski, Jerzy 1958. "Torsion textures produced by deformation and by dynamic recrystallization in a-iron and two IF steels." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40311.

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The textures of two IF steels and a high purity $ alpha$-iron were determined after deformation in torsion over the temperature range 20-840$ sp circ$C. The three characteristic bcc torsion fibres are described in detail and the locations of some important ideal orientations are identified on the $ {110 }$ pole figure. At room temperature, these are the F(110)(001), J1 (011) (211), J2 (110) (112), D1 (112) (111), D2 (112) (111), E1 (011) (111) and E2 (011) (111). At elevated temperatures, the conditions were chosen so that dynamic recrystallization (DRX) took place in the ferrite and that static recrystallization was avoided during cooling after deformation. The DRX textures differ from those observed at room temperature and are dominated by the D2 (112) (111), D1 (112) (111) and E2 (011) (111) components. The D2 becomes increasingly important as the strain is increased, which leads to weakening of the D1 and disappearance of the E2 at large strains.
Deformation textures were simulated using the rate sensitive theory of crystal plasticity. These called for lengthening to take place, in agreement with the measured length changes. The simulated and experimentally observed 'tilt' phenomena are similar to those commonly reported in the literature for fcc materials. The explanation of this phenomenon developed for the latter materials is extended to bcc metals. The development of torsion textures is discussed in terms of the rotation rate vector R, the divergence-convergence properties of orientation flow, and the stability parameter S.
DRX textures were simulated using a model based on sequential deformation, nucleation and growth steps. The types of oriented nucleation and selective growth required to reproduce the experimentally observed textures are discussed. The simulations indicate that the low energy nucleation mechanism plays a dominant role in the formation of bcc DRX textures. The results are also interpreted in terms of the continuous (in situ) and discontinuous mechanisms of dynamic recrystallization.
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26

Cardoso, Geraldo I. S. L. "The influence of microstructure on the hot ductility of four low carbon steels with respect to transverse crack formation in continuously cast slabs /." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59567.

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The influence of Al, Mn and Ti on the hot ductility of four low C steels has been examined.
Ductility troughs were exhibited by all the steels. These could be related to the austenite-to-ferrite phase transformation and grain boundary precipitation behavior. When no precipitation took place at the austenite grain boundaries, the trough occurred by intergranular failure. Fracture surfaces revealed microvoid coalescence, with voids associated with MnS inclusions.
Increasing the Mn in the steels lowers the $ gamma to alpha$ transformation temperature, causing the trough to be moved to lower temperatures. It also decreases the volume fraction of MnS inclusions within the ferrite film. Increasing the Al level caused AlN to be precipitated at the austenite grain boundaries, extending the trough to higher temperatures into the single phase austenite region.
The addition of Ti results in a fine austenite grain size after the solution treatment and impedes AlN precipitation. This leads to improved ductility in the austenite region.
When austenite recrystallization occurs during deformation, any voids which have initiated at the boundaries are trapped within the newly recrystallized grains. Intergranular failure cannot progress and the ductility is high.
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27

Roucoules, Christine. "Dynamic and metadynamic recrystallization in HSLA steels." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39794.

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A Mo, a Nb and a Ti steel were tested in torsion to study the characteristics of dynamic and postdynamic recrystallization. To characterize dynamic recrystallization, continuous torsion tests were carried out between 850 and 1050$ sp circ$C at strain rates of 0.02, 0.2 and 2s$ sp{-1}.$ Quenches were performed to investigate the grain refinement produced by dynamic recrystallization. Interrupted torsion tests were performed between 850 and 1050$ sp circ$C and at strain rates between 0.02 and 2s$ sp{-1}$ to study the characteristics of postdynamic recrystallization. Quenches were performed after increasing holding times to follow the evolution of the postdynamic microstructure. The evolution of the grain size distribution as a function of holding time shows that the growth of dynamically recrystallized grains is the first change that takes place. Then metadynamically recrystallized grains appear and contribute to the softening of the material. The rate of metadynamic recrystallization increases with strain rate and temperature and is observed to be independent of strain, in contrast to the observations for static recrystallization. The dependence of the metadynamically recrystallized grain size on the Zener-Hollomon parameter was established and is shown to differ from static recrystallization dependence. Simple torsion simulations were carried out using constant interpass times to study the conditions under which dynamic, metadynamic or static recrystallization takes place. Dynamic recrystallization controlled rolling (DRCR) is shown to require such short interpass times that they are not attainable in hot strip mills. A new concept, metadynamic recrystallization controlled rolling (MDRCR), is introduced to describe the case where there is 20 to 80% softening by metadynamic recrystallization. The occurrence of dynamic and metadynamic recrystallization causes the load to increase less rapidly than in the case of pure strain accumulation.
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28

Barnett, Matthew R. "Influence of warm rolling temperature on ferrite recrystallization in low C and IF steels." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41976.

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Experiments involving single pass laboratory rolling and isothermal salt bath annealing were carried out; three steels were studied: a titanium stabilized interstitial free grade and two low carbon grades, one of which contained a particularly low level of manganese ($ sim$0.009wt.%). The two low carbon grades were produced such that any complication from AlN precipitation was avoided. X-ray, neutron diffraction, optical metallography and mechanical testing measurements were carried out on the samples before and after annealing. The main aim of this work was to further the understanding of the metallurgy of recrystallization after ferrite rolling at temperatures between room temperature and 700$ sp circ$C.
Deformation textures, recrystallization kinetics, final grain sizes and recrystallization textures were quantified for all the samples and experimental conditions. A major conclusion based on these data is that the influence of rolling temperature is far greater in the low carbon samples than in the IF grade. Indeed, the IF results alter only marginally with increasing temperature. In the low carbon grades, however, the rolling texture sharpens, recrystallization slows, the final grain size coarsens, and the recrystallization texture changes when the rolling temperature is increased.
This distinct difference between the two steel types is explained in terms of their contrasting deformation behaviors. Solute carbon and nitrogen in the low carbon grades interact with dislocations causing high stored energy levels after low temperature rolling (due to dynamic strain aging) and high strain rate sensitivities during high temperature rolling (due to the solute drag of dislocations in the transition region between DSA and DRC). Nucleation during subsequent recrystallization is strongly influenced by both the stored energy and the strain rate sensitivity. The latter affects the occurrence of the flow localisations that enhance nucleation.
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29

Saxena, Pawan. "Slip casting of silicon nitride." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56974.

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Slip casting is a well established technique for the manufacture of traditional ceramic bodies, such as clays and whitewares. It combines complex shaping with high green densities, resulting in low shrinkage and good densification behaviour.
This method, however, has received little attention in the field of engineering ceramics especially with regard to silicon nitride. Commercial fabrication of silicon nitride, a major contender for high temperature applications due to its excellent thermomechanical properties, has been confined to hot pressing. This is an expensive process and has geometrical limitations.
Slip casting, followed by sintering, has been identified as a potentially economical alternative fabrication method, however a number of parameters have to be optimized before a good slip cast silicon nitride body can be made. The aim of the present work is to control parameters such as pH, viscosity and deflocculation in order to form dense, homogeneous, slip cast silicon nitride bodies.
A detailed investigation of the rheological properties of Si$ sb3$N$ sb4$ and careful control of processing parameters, made it possible to produce slip cast Si$ sb3$N$ sb4$ bodies having up to 97% TD on sintering. Mechanical strength values obtained by slip casting were compared with those obtained by die-pressing. Strength values of the slip cast material was limited by iron inclusions entrained in processing.
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30

Li, Dongyang. "Texture formation in iron electrodeposits." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=29076.

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The texture of electrodeposits has attracted increasing interest, as it is recognized that it is a possible to benefit from the texture and to improve the various properties of electrodeposits or electrolytic coatings. For example, the corrosion resistance of materials is affected by texture. If appropriate textures are introduced in electrodeposited coatings, their corrosion resistance would be enhanced and the coatings will therefore have a longer service time. Texture development during electrodeposition is still poorly understood, and this makes it difficult to control the texture formation during the electrodeposition processes. In order to better understand the texture formation during electrodeposition, extensive theoretical and experimental investigation are undertaken in this thesis.
A computer model was proposed to describe texture development. In this model, the microstructure of deposit was represented using a two dimensional triangle lattice. The deposit growth was modelled as previously empty lattice sites are being occupied based on fundamental physical rules. The author proposed that the main driving force for the development of microstructure and texture is the minimization of the system's free energy. This results in texture development, and the minimization of the free energy includes deposit's surface energy and occasionally the magnetic energy. Based on this hypothesis, the texture formation during iron electrodeposition and its variation with the deposition condition were simulated. It was demonstrated that the crystallographic anisotropy of deposit's surface energy plays an important role in the formation of the deposit's fibre texture. The study also indicated that the surface-energy anisotropy could be modified by hydrogen co-deposition and the deposit's texture can be modified by varying the current density, temperature, or pH value of the bath. In addition, the study illustrated that the magnetization energy also plays an important role in texture development during electrodeposition of magnetic materials. When external magnetic fields of sufficient strength are applied during the deposition of magnetic materials, the magnetic fields align grains in such a way that the deposits' fibre textures may transform to non-fibre textures.
In order to further justify the minimum-energy texturing mechanism proposed in the model, and to obtain a clear physical picture of the texture formation during electrodeposition, the process of texture development was analyzed using classical thermodynamics. Various experiments were conducted to verify the computer simulation. A positive correlation between the results of the simulation and the experiments were found.
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31

Debray, Bruno. "Microstructure and mechanical properties of an as-hot rolled carbon manganese ferrite-bainite sheet steel." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69713.

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By means of torsion testing, the microstructures and mechanical properties produced in a 0.14%C-1.18%Mn steel were investigated over a wide range of hot rolling conditions, cooling rates and coiling temperatures. The reheating temperature was varied between 800$ sp circ$C and 1050$ sp circ$C, and strains between 0 and 0.8 were applied. This led to austenite grain sizes ranging from 10 to 150$ mu$m. Two cooling rates, 55$ sp circ$C/s and 90$ sp circ$C/s, were applied and cooling was interrupted at coiling temperatures ranging from 550$ sp circ$C to 300$ sp circ$C.
Optical microscopy and TEM were used to study the microstructures. The mechanical properties were studied by means of tensile testing. A method developed by IRSID for deducing the transformation kinetics from the cooling data was adapted to the present context and used successfully to interpret the observed influence of the process parameters. (Abstract shortened by UMI.)
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32

Zarandi, Faramarz MH. "The effect of high temperature deformation on the hot ductility of Nb-microalloyed steel /." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85109.

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Low hot ductility at the straightening stage of the steel continuous casting process, where the surface temperature ranges from 600 to 1200°C, is associated with transverse cracking on the billet surface. This is attributed to various microalloying elements, which are essential for the mechanical characteristics of the final products. Thermomechanical processing is a new approach to alleviate this problem. In this work, two grades of Nb-containing steel, one modified with B, were examined. In order to simulate the key parameters of continuous casting, specimens were melted in situ and subjected to thermal conditions similar to that occurring in a continuous casting mill. They were also deformed at different stages of the thermal schedule. Finally, the hot ductility was evaluated at the end of the thermal schedule, corresponding to the straightening stage in continuous casting at which the hot ductility problem occurs in the continuous casting process.
The results showed that the presence of B is noticeably beneficial to the hot ductility. Failure mode analysis was performed and the mechanism of fracture was elaborated. As well, the potential mechanisms under which B can improve the hot ductility were proposed.
Deformation during solidification (i.e. in the liquid + solid two phase region) led to a significant loss of hot ductility in both steels. By contrast, deformation in the delta-ferrite region, after solidification, was either detrimental or beneficial depending on the deformation start temperature.
The hot ductility was considerably improved in the steel without B when deformation was applied during the delta → gamma transformation. The effect of such deformation on the other steel grade was not significant. Examination of the microstructure revealed that such improvement is related to a grain refinement in austenite. Therefore, the effect of deformation parameters was studied in detail and the optimum condition leading to the greatest improvement in the hot ductility was determined.
Finally, some solutions to the industrial problem in the continuous casting process were proposed.
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33

Hassani, Farideddin. "Mechanical behaviour of steel near the incipient melting temperature." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69719.

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A new method of incipient melting temperature (IMT) detection, continuous heating and fracture (CHF) method, has been developed in which a constant strain rate tensile or torsion deformation is applied to a specimen whose temperature is simultaneously increased. The IMT is determined in a single test and any phase transformations before the IMT will also be detected by the effects on the stress vs. strain behavior in the same experiment. This method also provides information about the effect of phase transformation and temperature on the mechanical behaviour of steel near the incipient melting temperature.
By means of such tests, the incipient melting behaviour of a series of steels with carbon levels from 0.031 to 0.45 wt% was examined. For the steels containing 0.08-0.097%C and about 1.5%Mn, it was found that incipient melting occurs in the two phase ($ gamma$+$ delta$) region in the temperature range from 1470-1480$ sp circ$C, and is significantly influenced by microalloying elements. In the ultra-low carbon steel (0.031%C), the IMT is in the single phase $ delta$ region at 1495 $ sp circ$C, and for the medium carbon steels containing 0.3-0.42%C (hyper-peritectic) it is in the $ gamma$ single phase in the temperature range of 1401-1414$ sp circ$C. Comparison between the IMT obtained from CHF testing and the solidus temperature calculated from K-O model showed that these two values are extremely close. Since there is no nucleation barrier for melting, it seems that the CHF testing can delineate the solidus temperature in steel. (Abstract shortened by UMI.)
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34

Jiang, Lan 1970. "Effect of silicon on the interaction between recrystallization and precipitation in niobium microalloyed steels." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79236.

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The effect of Si addition on the interaction between recrystallization and precipitation during multipass deformation has been investigated in terms of the no-recrystallization temperature (Tnr), the minimum temperature at which recrystallization can be completed. The Tnr was measured in three Nb microalloyed steels with Si concentrations ranging from 0.01 to 0.48wt.%. Continuous cooling conditions were employed, with interpass times of 20--200s and strains of 0.2 and 0.35 applied at a strain rate of 2s -1.
It was observed that for similar Nb contents, the Tnr increased with Si level, but appeared to saturate at long interpass times. In addition, high strains also reduced the influence of Si on the Tnr. This behaviour can be attributed to the acceleration of the Nb(C,N) precipitation kinetics by the addition of Si. With increasing interpass time or strain, the precipitates start to coarsen and, in consequence, the pinning effect due to precipitation is reduced. Therefore, under these conditions, the effectiveness of Si addition in raising the Tnr is diminished.
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35

Elalem, Kaled. "Application of heat pipe technology in permanent mold casting of nonferrous alloys." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85067.

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The issue of mold cooling is one, which presents a foundry with a dilemma. On the one hand; the use of air for cooling is safe and practical, however, it is not very effective and high cost. On the other hand, water-cooling can be very effective but it raises serious concerns about safety, especially with a metal such as magnesium. An alternative option that is being developed at McGill University uses heat pipe technology to carry out the cooling.
The experimental program consisted of designing a permanent mold to produce AZ91E magnesium alloy and A356 aluminum alloy castings with shrinkage defects. Heat pipes were then used to reduce these defects. The heat pipes used in this work are novel and are patent pending. They are referred to as McGill Heat Pipes.
Computer modeling was used extensively in designing the mold and the heat pipes. Final designs for the mold and the heat pipes were chosen based on the modeling results.
Laboratory tests of the heat pipe were performed before conducting the actual experimental plan. The laboratory testing results verified the excellent performance of the heat pipes as anticipated by the model.
An industrial mold made of H13 tool steel was constructed to cast nonferrous alloys. The heat pipes were installed and initial testing and actual industrial trials were conducted. This is the first time where a McGill heat pipe was used in an industrial permanent mold casting process for nonferrous alloys.
The effects of cooling using heat pipes on AZ91E and A356 were evaluated using computer modeling and experimental trials. Microstructural analyses were conducted to measure the secondary dendrite arm spacing, SDAS, and the grain size to evaluate the cooling effects on the castings. The modeling and the experimental results agreed quite well. The metallurgical differences between AZ91E and A356 were investigated using modeling and experimental results. Selected results from modeling, laboratory and industrial trials are presented. The results show a promising future for heat pipe technology in cooling permanent molds for the casting of nonferrous alloys.
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36

Akbarzadeh, Abbas. "Effect of thermomechanical processing on microstructure, texture, and anisotropy in two Nb microalloyed steels." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq29871.pdf.

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37

Gettens, Robert T. T. "Protein adsorption onto medical alloys voltage effects /." Related electronic resource:, 2007. http://proquest.umi.com/pqdweb?did=1398611421&sid=1&Fmt=2&clientId=3739&RQT=309&VName=PQD.

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38

McWilliams, Brandon A. Zavaliangos Antonios. "Numerical simulation of electric field assisted sintering /." Philadelphia, Pa. : Drexel University, 2008. http://hdl.handle.net/1860/2763.

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39

Sole, Kathryn Clare. "Solvent extraction of first-row transition metals by thiosubstituted organophosphinic acids." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186480.

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Organophosphorus compounds are well known as solvent-extraction reagents. Two new reagents in this class are Cyanex 302 and Cyanex 301, the respective mono- and dithio analogs of the commercial extractant, Cyanex 272 (bis(2,4,4-trimethylpentyl)-phosphinic acid). The replacement of oxygen by sulfur in these reagents decreases their pKₐ, and enables extraction to be carried out at much lower pH than previously attained. A comparative characterization of Cyanex 272, Cyanex 302, and Cyanex 301 is undertaken. The aggregation and partitioning behavior of these reagents is determined. A comparison of the solvent extraction behavior of first-row transition-metal ions from manganese to zinc in acidic sulfate solution by these reagents is reported. Distribution coefficients shift to lower pH with increasing sulfur substitution of the extractant, the greatest effect being observed for soft Lewis acids. These reagents are found to be strong extractants for the transition metals examined, but poor extractants for alkaline-earth ions and manganese(II). Certain metal ions, in particular copper(II) and silver(I), are, however, extremely difficult to strip, which may mitigate against potential applications. Stoichiometry of the extraction reactions and the nature of the metal complexes formed are postulated based on slope-analysis techniques and spectroscopic and molecular-mass measurements. Molecular modelling of the extractants and extracted species is presented. Some reasons for the enhanced stability of the complexes formed with certain metals are discussed in terms of d-electron effects, donor-/acceptor-atom interactions, ligand-field observations, and steric effects associated with the extractants.
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40

Zhang, Bin. "Fatigue behavior in an aluminum casting alloy (A356.2): Effects of some defects, SDAS, Hipping and strontium modification." Diss., The University of Arizona, 2002. http://hdl.handle.net/10150/280228.

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Effects of pore, secondary dendrite arm spacings (SDAS ), hot isostatic pressing (Hipping), and strontium-modification on fatigue behavior were studied in an aluminum casting alloy (A356.2). Microstructures were revealed by X-ray radiography, light microscopy and scanning electron microscopy. Small-cracks were monitored by taking replicas of the surfaces with which the cracks intersected. As the SDAS increases from 15 to 55 μm, fatigue life decreases by a factor of 3 in low-cycle fatigue, and 100 in high-cycle fatigue. When SDAS is less than 30 mum, the pore size is below a critical size of ∼80 μm and large eutectic constituents initiate cracks; and the initiation life is as high as 70% of the fatigue life. As the SDAS increases beyond 30 μm, pores are the main crack-initiation sites; the initiation life is as low as 5% of the fatigue life. Near-surface oxides initiate the fatigue crack regardless of SDAS. When crack initiated at pore and oxides, fatigue life is well correlated with the size of the initiation site and the effect of SDAS is overshadowed by the effect of pore. Non-hipped A356.2 without Sr shows better fatigue life and the deleterious effect of pores overshadowed the beneficial effect that Sr-modification might have had. Hipping significantly increased the initiation life and small-crack propagation life of A356.2 with Sr as a result of the elimination of the porosity. However, hipping did not significantly improve the fatigue life of A356.2 without Sr. After hipping, Sr-modification is beneficial in improving the crack initiation life, and increasing both small-crack and long-crack propagation lives. Fracture mechanics models (Newman-Raju, and Trantina-Barishpolsky models) yielded similar results on the crack-propagation rate against the effective stress-intensity factor range. In the micro-mechanics model, the theory of continuously distributed dislocations was applied to represent crack and crack-tip plastic zone, and the propagation rate was related to the length of the crack-tip plastic zone. When the grain size is used as the characteristic length of the microstructures, the model predicts the oscillations of the propagation rates and the predicted rates agreed reasonably well with those from experiments.
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41

Moats, Michael Scott 1970. "Electrochemical characterization of anode passivation mechanisms in copper electrorefining." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282777.

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Anode passivation can decrease productivity and quality while increasing costs in modern copper electrorefineries. This investigation utilized electrochemical techniques to characterize the passivation behavior of anode samples from ten different operating companies. It is believed that this collection of anodes is the most diverse set ever to be assembled to study the effect of anode composition on passivation. Chronopotentiometry was the main electrochemical technique, employing a current density of 3820 A m⁻². From statistical analysis of the passivation characteristics, increasing selenium, tellurium, silver, lead and nickel were shown to accelerate passivation. Arsenic was the only anode impurity that inhibited passivation. Oxygen was shown to accelerate passivation when increased from 500 to 1500 ppm, but further increases did not adversely affect passivation. Nine electrolyte variables were also examined. Increasing the copper, sulfuric acid or sulfate concentration of the electrolyte accelerated passivation. Arsenic in the electrolyte had no effect on passivation. Chloride and optimal concentrations of thiourea and glue delayed passivation. Linear sweep voltammetry, cyclic voltammetry, and impedance spectroscopy provided complementary information. Analysis of the electrochemical results led to the development of a unified passivation mechanism. Anode passivation results from the formation of inhibiting films. Careful examination of the potential details, especially those found in the oscillations just prior to passivation, demonstrated the importance of slimes, copper sulfate and copper oxide. Slimes confine dissolution to their pores and inhibit diffusion. This can lead to copper sulfate precipitation, which blocks more of the surface area. Copper oxide forms because of the resulting increase in potential at the interface between the copper sulfate and anode. Ultimate passivation occurs when the anode potential is high enough to stabilize the oxide film in the bulk electrolyte. The effect of anode impurities or electrolyte concentrations can be related to the formation of one of these films. Reactions occurring after passivation have also been examined. Post-passivation reactions are believed to include silver dissolution, transformation of lead sulfate to lead oxide, and oxygen evolution. Following the sharp potential increase caused by the passivation, silver that has accumulated on the anode surface will dissolve into the electrolyte at a potential between 1.0 and 1.3 V. After the silver has dissolved, the potential increases again at which point the oxidation of lead sulfate to lead oxide occurs. The formation of lead oxide provides a surface with a lower oxygen evolution overpotential. The presence of kupferglimmer also results in a stable lower oxygen evolution potential occurring at approximately 2.0 V.
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42

Cherne, Frank Joseph. "Calculation of transport properties of liquid metals and their alloys via molecular dynamics." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284305.

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The advanced casting modeler requires accurate viscosity and diffusivity data of liquid metals and their alloys. The present work discusses the use of equilibrium and non-equilibrium molecular dynamics techniques to obtain such data without having to rely on oversimplified phenomenological expressions or difficult and expensive experiments. Utilizing the embedded atom method (EAM), the viscosities and diffusivities for a series of equilibrium and non-equilibrium molecular dynamics simulations of nickel, aluminum, and nickel-aluminum alloys are presented. A critical comparison between the equilibrium and non-equilibrium methods is presented. Besides the transport properties, structural data for the liquids are also evaluated. EAM does a poor job of describing the transport properties of nickel-aluminum alloys, particularly near the equiatomic concentration. It has been suggested that charge transfer between nickel and aluminum atoms is responsible for the discrepancy between numerical calculations and available experimental data. A modified electronic distribution function has been developed to simulate the charge transfer associated with compound formation. The effects of such a "charge transfer" modification to the embedded atom method are evaluated. The results of these simulations indicate that the embedded atom method combined with molecular dynamics may be used as a method to predict reasonably the transport properties.
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43

Apprill, Jon M. 1974. "Process control of GASAR porous metals." Thesis, The University of Arizona, 1998. http://hdl.handle.net/10150/291491.

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GASAR porous metals are produced by melting under a partial pressure of hydrogen and then casting into a mold that ensures directional solidification. Hydrogen is driven out of solution and grows as cylindrical pores normal to the solidification front. Experiments have been performed to produce GASARs from pure Ni and Inconel 718, a nickel-base superalloy. The processing variables studied in these experiments included the pressure of H₂(g), total pressure, superheat, and solidification rate. An analysis that considers heterogeneous bubble nucleation was developed that identifies processing conditions in which H₂(g) bubbles are stable in the liquid before solidification. It is hypothesized that these conditions lead to low porosity because the bubbles float out of the melt and are not incorporated into the final porosity. Experimental data are shown to support this hypothesis.
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44

Frueh, Christian 1969. "The effect of silica-containing binders on the titanium/face coat reaction." Thesis, The University of Arizona, 1995. http://hdl.handle.net/10150/291718.

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The interactions of CP-Ti and Ti-6Al-4V with investment molds with alumina/silica and yttria/silica face coat systems, and yttria crucibles were studied. It was found that the thickness of the reaction layer (alpha case) was the same, whether a yttria/silica or alumina/silica face coat was used, indicating that it is the silica binder truly which reacts with the titanium. Furthermore, it was found that only the yttria crucible was inert to reacting with titanium when it was used as a mold. When titanium was heated in yttria crucibles, however, and held just above the liquidus for 15 s and 30 s, oxygen and yttrium were found in the resulting samples. This indicates that commercial castings requiring longer solidification times might not be free of the alpha case even when produced in a 100% yttria mold system.
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45

Kannan, Manigandan. "A Study of Microstructure, Quasi-Static Response, Fatigue, Deformation and Fracture Behavior of High Strength Alloy Steels." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1417552570.

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46

Lan, Song. "High Temperature Nitridation of Powder and Nanocomposite Iron-based Magnetic Alloys." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1527853642053372.

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47

Wang, Tianxue. "DYNAMIC BEHAVIOR OF COMMERCIAL PURITY POLYCRYSTALLINE MAGNESIUM AT ELEVATED TEMPERATURES AND HIGH STRAIN-RATES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case156233794566219.

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48

Söderlind, Andreas, and August Forsström. "Riktlinjer för styrning av gastryck vid gasatomisering samt kartläggning av pulveregenskaper." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-23008.

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High quality powder steel is manufactured through gas atomization at Erasteel Kloster AB in Söderfors. During their batches they have a problem with varying weight of capsules which can cause problems with bending capsules and unreliable exchange. Bent capsules risk damaging the equipment and cannot be used.The work was performed with the purpose to investigate the source for varying weights of capsules during batches and with the goal to account for a solution on how the varying capsule weights can be reduced.Powder samples were taken during five batches aiming to investigate the cause for varying capsule weights. The powders characteristics were analyzed with different methods which presented the powders size distribution, fill density, tap density and flowability. The Lubanska equation which calculates powders mean diameter was simplified and adjusted for the Erasteel plant with the intention to control gas pressure depending on the metal flow rate.Analyzes showed that the powder size distribution was changing during every batch. The amount of larger particles decreased more than the amount of small particles increased meanwhile the width of the powders size distribution decreased. This gave the largest width of size distribution half-way into the batch and the highest capsule weights were obtained at this moment.The simplified equation was applied to the moment when highest capsule weights was obtained and gave guidelines on how the gas pressure should be controlled to achieve similar size distribution. Further analyzes showed that the metal flow rate was proportional to the gas temperature due to it is measured after being in contact the melt stream.Since the equation was simplified and verified on five batches more tests needs to be extracted. It needs to be done not only to get a more reliable equation but also for an opportunity to test it in practice. With samples collected from more batches, there is a possibility to control the gas pressure with gas temperature and an automatic control of the gas pressure could be performed.
På Erasteel Kloster AB i Söderfors tillverkas högkvalitativt pulverstål genom gasatomisering. De har ibland under deras körningar problem med varierande kapselvikter vilket kan ge problem med att kapslar veckas vid komprimering samt opålitligt utbyte. Veckade kapslar riskerar att skada komprimeringsutrustningen samtidigt som kapseln måste skrotas. Arbetet utfördes i syftet att undersöka orsaken till varför kapselvikterna varierar under chargerna och med målet att redogöra för hur variationerna på kapselvikterna kan minskas. Under fem körningar togs pulverprover ut för att undersöka orsaken till varför kapselvikterna varierar. Pulvrets egenskaper analyserades med olika metoder vilka gav pulvrets storleksfördelning, fylldensitet, skakdensitet samt flytbarhet. Den Lubanska ekvationen för att beräkna pulvers medeldiameter vid gasatomisering förenklades och anpassades till Erasteels anläggning för att anpassa gastryck efter metallflöde. Analysen visade att pulvrets storleksfördelning förändrades under samtliga körningar. Mängden stora pulverkorn minskade mer än vad mängden små pulverkorn ökade under atomiseringen. Detta medförde att den största variationen av stora och små pulverkorn var halvvägs in i chargen och vid denna tidpunkt erhölls även de högsta kapselvikterna. Den förenklade ekvationen gav, med hjälp av tidpunkten då kapselvikterna var som högst, riktlinjer för hur gastrycket bör styras för att uppnå liknande storleksfördelning. Ytterligare analyser visade att gastemperaturen var proportionellt mot metallflödet, då temperaturen mättes efter att gasen varit i kontakt med det rinnande stålet. Eftersom den tillämpade ekvationen förenklades och verifierades mot endast fem körningar borde fler tester utföras. Detta för att ge en mer tillförlitlig styrning samt möjligheten att testa ekvationens riktlinjer i praktiken. Med provuttag under flera charger finns möjligheten att styra gastryck mot gastemperatur och med hjälp av detta skapa en automatiserad styrning.
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49

Lu, Jian 1964. "Computer modeling of intergranular fracture in textured materials." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39950.

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An integrated computer simulation employing the Embedded-atom method (EAM), Molecular dynamics (MD), and Markov Chain Fracture models has been constructed and applied to study the intergranular fracture of brittle polycrystalline materials at both the atomistic and microscopic levels. At the atomistic level, the computer model is capable of treating bicrystals under the influence of external load and temperature with dynamic periodic boundary conditions along the grain boundary plane and a dynamic boundary condition perpendicular to the grain boundary plane. At the microscopic level, the computer model is capable of treating the sample with microstructure defined by the grain boundary character distribution under the influence of an external load to predict the intergranular fracture propagation under stress.
The fracture behavior of many $ Sigma$ grain boundaries has been investigated at the atomistic level for Cu, Ni, and Ni$ sb3$Al, and the fracture resistance of the grain boundary was predicted. It has been found that grain boundary energy and fracture resistance greatly depend on the grain boundary structure. Symmetrical $ Sigma$3 twin boundaries and low angle $ Sigma1$ boundaries are particularly strong in resisting intergranular fracture, while some other low $ Sigma$ boundaries are also strong, but grain boundaries with high energies are not at all fracture resistant. The calculated correlation between fracture resistance and misorientation of grain boundaries is in accordance with the experimental data. The calculated fracture resistances of the grain boundaries for Ni$ sb3$Al alloy are not significantly different from those for pure Ni. This suggests that the tendency to intergranular fracture is not due merely to the poor fracture resistance of grain boundaries. One must also consider the overall grain boundary character distribution.
In order to find the role of grain boundary character distribution on the intergranular fracture in brittle polycrystalline materials, the crack path, crack arrest distance, and fracture toughness have been investigated at the microscopic level with the different fraction of low-energy grain boundaries, grain boundary fracture resistance, orientation distribution of grain boundary planes, and grain shape factor. The simulations have indicated that with an increase in the fraction of low energy grain boundaries, the fracture toughness increases while the crack arrest distance decreases. With an increase in the number of low energy grain boundaries which are aligned parallel to the stress axis, one observes an increase in the fracture toughness and a decrease in the crack arrest distance. By increasing the grain shape factor, the fracture toughness decreases while the crack arrest distance increases.
If five grain diameter is defined as the critical length, and more than 25% of grain boundaries are of low-energy with the highest fracture resistance, such as $ Sigma$3 twin grain boundaries, the intergranular crack formed initially cannot propagate further due to the presence of fewer random boundaries, and the polycrystalline materials will show high ductility. The improvement in fracture toughness of Ni$ sb3$Al brittle polycrystal is due to the introduction of a high frequency of low energy grain boundaries (up to 70% by experimental treatments). Grain boundary design and control achieved by manipulating the grain boundary character distribution (GBCD) are important to fracture toughness improvement of the brittle polycrystal materials.
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50

Tidefelt, Mattias. "Coupled flux nucleation model applied to the metallic glass AMZ4." Thesis, Malmö universitet, Malmö högskola, Institutionen för materialvetenskap och tillämpad matematik (MTM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-42310.

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Additive manufacturing (AM), also known as 3D-printing, has made it possible to produce components made of bulk metallic glass (BMG) which have remarkable properties compared to parts made of conventional alloys. A metallic glass is a metastable noncrystalline alloy that form if a melt is quenched with a sufficient cooling rate. Research on systems with low critical cooling rates have made the maximum dimensions of these alloys to grow to what is called BMG's. The high local cooling rate obtained during AM makes it in principle possible to bypass the dimension restrictions that otherwise have been present when creating these alloys but the procedure is complex. It is believed that oxygen impurities in the powder feedstock material used during AM of Zr-based alloys makes it favourable for nucleation of stable crystalline phases at lower activation energies which hinders fully glass features to develop. The purpose of this thesis is to investigate how the limiting solute concentration in the bulk of the AM produced alloy AMZ4 (Zr59.3Cu28.8Al10.4Nb1.5(at\%)) impact the nucleation. Using a numerical model based on classical nucleation theory (CNT) that couples the interfacial and long range fluxes makes it possible to study how impurities impact the nucleation event. However, missing oxygen dependent data makes this a study on how limiting solute impact the nucleation in AMZ4. The numerical model is validated against earlier work and the results obtained from the simulations on AMZ4 shows a strong connection between the nucleation event and the limiting solute concentration. Further investigations on phase separation energies and the production of concentration dependent time-temperature-transformation (TTT) diagrams are needed to fully describe the connection to oxygen concentration. Nevertheless, the implemented model captures important features that the classical model cannot describe which needs to be taken into account when describing the nucleation in AMZ4.
Friformsframställning (eng. additive manufacturing (AM)), också känt som 3D-printing, har gjort det möjligt att producera komponenter gjorda av bulkmetallglas (eng. bulk metallic glass (BMG)) vilka har anmärkningsvärda egenskaper jämfört med delar gjord av konventionella legeringar. Ett metalliskt glas är en metastabil icke kristallin legering som skapas om en smälta släcks med en tillräcklig kylhastighet. Forsking på system med låga kritiska kylhastigheter har gjort att de maximala dimensionerna av dessa legeringar har ökat till vad som kallas BMG's. Den höga lokala kylhastigheten som erhålls under AM gör att  dimensionsrestriktionerna principiellt kan kringgås vilka annars är närvarande vid skapandet dessa legeringar men proceduren är komplex. Det är trott att orenheter av syre i pulver-råvarumaterialet som används vid AM av Zr-baserade legeringar gör det fördelaktigt för kärnbildning av stabila kristallina faser vid lägre aktiveringsenergier vilket hindrar fulla glas egenskaper från att utvecklas. Syftet med denna uppsats är att undersöka hur den begränsande lösningen påverkar kärnbildningsförloppet i den AM producerade legeringen AMZ4 (Zr59.3Cu28.8Al10.4Nb1.5(at\%)). En numerisk modell baserad  på klassisk kärnbildningsteori (eng. classical nucleation theory (CNT)) som kopplar gränsskikt- och långdistans-flödet gör det möjligt att studera hur orenheter påverkar kärnbildningsförloppet. Syreberoende data gör dock detta till en studie om hur den begränsande lösningen påverkar kärnbildningen i AMZ4. Den numeriska modellen valideras mot tidigare arbeten och resultaten från simuleringarna av AMZ4 visar ett starkt samband mellan kärnbildningsförloppet och den begränsade lösningskoncentrationen. Vidare studier rörande fas-separeringsenergier och framställningen av koncentrationsberoende tid-temperature-transformation (eng. time-temperature-transformation (TTT)) diagram behövs för att till fullo beskriva kopplingen till syrekoncentrationen. Den implementerade modellen fångar dock viktiga egenskaper som den klassiska modellen inte kan beskriva vilka måste tas hänsyn till när kärnbildning i AMZ4 ska beskrivas.
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