A Study of Phase Transformations and Microstructural Evolution in Cu-Ge Alloys PDF Download
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Author: Sumanth Jagga
Publisher:
ISBN:
Category :
Languages : en
Pages : 242
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Author: Sumanth Jagga
Publisher:
ISBN:
Category :
Languages : en
Pages : 242
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Author: J Lin
Publisher: Elsevier
ISBN: 0857096346
Category : Technology & Engineering
Languages : en
Pages : 409
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Book Description
Monitoring and control of microstructure evolution in metal processing is essential in developing the right properties in a metal. Microstructure evolution in metal forming processes summarises the wealth of recent research on the mechanisms, modelling and control of microstructure evolution during metal forming processes.Part one reviews the general principles involved in understanding and controlling microstructure evolution in metal forming. Techniques for modelling microstructure and optimising processes are explored, along with recrystallisation, grain growth, and severe plastic deformation. Microstructure evolution in the processing of steel is the focus of part two, which reviews the modelling of phase transformations in steel, unified constitutive equations and work hardening in microalloyed steels. Part three examines microstructure evolution in the processing of other metals, including ageing behaviour in the processing of aluminium and microstructure control in processing nickel, titanium and other special alloys.With its distinguished editors and international team of expert contributors, Microstructure evolution in metal forming processes is an invaluable reference tool for metal processors and those using steels and other metals, as well as an essential guide for academics and students involved in fundamental metal research. - Summarises the wealth of recent research on the mechanisms, modelling and control of microstructure evolution during metal forming processes - Comprehensively discusses microstructure evolution in the processing of steel and reviews the modelling of phase transformations in steel, unified constitutive equations and work hardening in microalloyed steels - Examines microstructure evolution in the processing of other materials, including ageing behaviour in the processing of aluminium
Author: Patrice E. A. Turchi
Publisher: Minerals, Metals, & Materials Society
ISBN:
Category : Science
Languages : en
Pages : 432
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Book Description
This is a collection of papers presented at the TMS Annual Meeting & Exhibition, held in Nashville, Tennessee, in March, 2000. The symposium emphasizes both theoretical and experimental aspects of phase transformations and evolutions in materials. Topics addressed in papers include: mechanical properties of structurally heterogeneous systems; simulations of structural transformations; large-scale modelling of microstructure evolution in martensites; applying the concentration wave method to predict ordering phenomena in substitutional alloys and ceramic materials; and use of the phase field method to study coherent transformations.
Author: Taiwu Yu
Publisher:
ISBN:
Category : Martensitic transformations
Languages : en
Pages : 0
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Book Description
Phase transformation is always a critical topic in the study of materials science. Most people have been familiar with some transformations between solid and liquid, such as ice to water, or transformations between liquid and gas, such as water to vapor. Besides, the phase transformations in solids also occur everywhere. Some solid phase transformations occur due to temperature variations. Those transformations may also be affected by external stress or strain, as seen in shape memory alloys (SMAs). The solid-solid transformation is considered to be the one of the most effective ways to tailor the microstructure and properties of the alloys, moreover, it sometimes strengthens the structural materials. There are some types of solid-state phase transformations that are hard to characterize in the traditional experiments. The difficulty mainly comes from two aspects. Firstly, some of the phase transformations happen too fast, such as martensitic transformation. The speed of the martensitic transformation is close to the speed of sound traveling in solids (~1000m/s), which makes it difficult to know how it starts and evolves. Secondly, some of the phase transformation processes are too slow, such as oxidation. It could take years to form a continuous layer of oxides in microns. With the fast development of high-performance computing, the study of phase transformations through computational tools attracts more and more attention. The objective of this thesis is to apply computational tools to study the two types of phase transformations and their corresponding mechanical properties: precipitation and martensitic transformation. As one of the most important structural phase transformations discovered in metallurgy and materials science, martensitic transformation (MT) has been attracting continued attention since its discovery in the late nineteenth century till today because it relates closely to the functional properties of NiTi-based alloy such as the superelasticity and shape memory effect. Most importantly, MT can be tailored through nano-scale defects in materials. Firstly, nano-scale defects in the B2 parent phase are known to have profound impacts on the properties of NiTi-based shape memory alloys. We employed the phase field models (PFM) to study the effects of two typical nano-scale defects, nano-scale precipitates and voids, on MT. The simulation of precipitation unveiled the mechanical and chemical effects on the behavior of MT in NiTi-Hf alloys. Moreover, the simulation of MT with the coexistence of precipitates explained the mechanism of two typical patterns of martensite. The results indicates that the stress-strain response has great dependence on the concentration heterogeneity in the matrix as well as precipitate microstructures. Through the simulation we proved the feasibility to achieve linear or quasi-linear superelasticity with high recoverable strain (up to 4%) in NiTi-Hf alloys after the precipitation. In the simulation of MT under the effects of nano voids in NiTi, we observed that martensite could be confined in the interspacing area between voids. Besides, MT could be triggered at lower critical stress with larger volume fraction of voids. This simulation may shed lights on the design of the porous NiTi alloys for the biomedical application. In superalloys, the microstructure of precipitates can be altered by the formation of an oxide layer on the surface. It is observed that the \gamma\prime precipitates dissolve at the near-surface region with the formation of the oxide layer in the alloy. We employed DICTRA module in Thermo-calc Software to solve the multicomponent diffusion equations in alloy H282 with an outward flux of chromium or aluminum due to oxidation and applied PFM to simulate the dissolution of precipitates. The local variation of precipitates’ volume fraction as a function of oxidation time has been quantitatively determined. The calculation of precipitates depletion depth shows good agreement with the experiments. The highly heterogeneous structure of \gamma\prime precipitates is expected to have a significant effect on the creep behavior of the alloy.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 702
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Author: Jun Yang
Publisher:
ISBN:
Category :
Languages : en
Pages : 222
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Author:
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages : 2566
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Author: Smita Gangaprasad Rao
Publisher: Linköping University Electronic Press
ISBN: 9179296688
Category :
Languages : en
Pages : 28
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Book Description
The need for materials that enhance life span, performance, and sustainability has propelled research in alloy design from binary alloys to more complex systems such as multicomponent alloys. The CoCrFeMnNi alloy, more commonly known as the Cantor alloy, is one of the most studied systems in bulk as well as thin film. The addition of light elements such as boron, carbon, nitrogen, and oxygen is a means to alter the properties of these materials. The challenge lies in understanding the process of phase formation and microstructure evolution on addition of these light elements. To address this challenge, I investigate multicomponent alloys based on a simplified version of the Cantor alloy. My thesis investigates the addition of nitrogen into a Cantor variant system as a step towards understanding the full Cantor alloy. Me1-yNy (Me = Cr + Fe + Co, 0.14 ≤ y ≤0.28 thin films were grown by reactive magnetron sputtering. The films showed a change in structure from fcc to mixed fcc+bcc and finally a bcc-dominant film with increasing nitrogen content. The change in phase and microstructure influenced the mechanical and electrical properties of the films. A maximum hardness of 11 ± 0.7 GPa and lowest electrical resistivity of 28 ± 5 μΩcm were recorded in the film with mixed phase (fcc+bcc) crystal structure. Copper was added as a fourth metallic alloying element into the film with the mixed fcc + bcc structure, resulting in stabilization of the bcc phase even though Cu has been reported to be a fcc stabilizer. The energy brought to the substrate increases on Cu addition which promotes surface diffusion of the ions and leads to small but randomly oriented grains. The maximum hardness recorded by nanoindentation was found to be 13.7 ± 0.2 GPa for the sample Cu0.05. While it is generally believed that large amounts of Cu can be detrimental to thin film properties due to segregation, this study shows that small amounts of Cu in the multicomponent matrix could be beneficial in stabilizing phases as well as for mechanical properties. This thesis thus provides insights into the phase formation of nitrogen-containing multicomponent alloys.
Author: Ping Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 268
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Author: David A. Porter
Publisher: CRC Press
ISBN: 1439883572
Category : Science
Languages : en
Pages : 538
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Book Description
Expanded and revised to cover developments in the field over the past 17 years, and now reprinted to correct errors in the prior printing, Phase Transformation in Metals and Alloys, Third Edition provides information and examples that better illustrate the engineering relevance of this topic. It supplies a comprehensive overview of specific types o
