[PDF] Recrystallization Mechanisms In Wrought Magnesium Alloys Containing Rare Earth Elements eBook

Author : Aidin Imandoust
Publisher :
Page : 176 pages
File Size : 29,12 MB
Release : 2017
Category :
ISBN :

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The origin of texture components associated with rare-earth (RE) element additions in wrought magnesium (Mg) alloys is a long-standing problem in magnesium technology. The objective of this research is to identify the mechanisms accountable for rare-earth texture during dynamic recrystallization (DRX). Towards this end, we designed binary Mg-Cerium and Mg-Gadolinium alloys along with complex alloy compositions containing zinc, yttrium and Mischmetal. Binary alloys along with pure Mg were designed to individually investigate their effects on texture evolutions, while complex compositions are designed to develop randomized texture, and be used in automotive and aerospace applications. We selected indirect extrusion to thermo-mechanically process our materials. Different extrusion ratios and speeds were designed to produce partially and fully recrystallized microstructures, allowing us to analyze DRX from its early stages to completion. X-ray diffraction, electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were used to conduct microstructure and texture analyses. Our analyses revealed that rare-earth elements in zinc-containing magnesium alloys promote discontinuous dynamic recrystallization at the grain boundaries. During nucleation, the effect of rare earth elements on orientation selection was explained by the concomitant actions of multiple Taylor axes in the same grain. Isotropic grain growth was observed due to rare earth elements segregating to grain boundaries, which lead to texture randomization. The nucleation in binary Mg-RE alloys took place by continuous formation of necklace structures. Stochastic relaxation of basal and non-basal dislocations into lowangle grain boundaries produced chains of embryos with nearly random orientations. Schmid factor analysis showed a lower net activation of dislocations in RE textured grains compared to ones on the other side of the stereographic triangle. Lower dislocation densities within RE grains favored their growth by setting the boundary migration direction toward grains with higher dislocation density, thereby decreasing the system energy. We investigated the influence of RE elements on extension twinning induced hardening. RE addition enhanced tensile twinning induced hardening significantly. EBSD analysis illustrated that tensile twins cross low angle grain boundaries in Mg-RE alloys, which produced large twins and facilitated transmutation of basal to prismatic dislocations. Higher activity of pyramidal II dislocations in Mg-RE alloys resulted in higher twinning induced hardening.

Author : Kiran N. Solanki
Publisher : Springer
Page : 642 pages
File Size : 12,27 MB
Release : 2017-02-14
Category : Technology & Engineering
ISBN : 3319523929

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The Magnesium Technology Symposium, the event on which this collection is based, is one of the largest yearly gatherings of magnesium specialists in the world. Papers represent all aspects of the field, ranging from primary production to applications to recycling. Moreover, papers explore everything from basic research findings to industrialization. Magnesium Technology 2017 covers a broad spectrum of current topics, including alloys and their properties; cast products and processing; wrought products and processing; forming, joining, and machining; corrosion and surface finishing; ecology; and structural applications. In addition, there is coverage of new and emerging applications.

Author : L.L. Rokhlin
Publisher : CRC Press
Page : 256 pages
File Size : 39,86 MB
Release : 2003-02-20
Category : Science
ISBN : 1482265168

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Magnesium-based alloys containing rare-earth metals are important structural materials, as they combine low density with high-strength properties. This makes them particularly attractive for industry, especially in cases where the low weight of constructions is critical, as in aircraft and space apparatus construction. One of the remarkable feature

Author : Christian Wetzel
Publisher : Cambridge University Press
Page : 0 pages
File Size : 26,61 MB
Release : 2005-07-01
Category : Technology & Engineering
ISBN : 9781558997790

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This book discusses GaN and Related Alloys and reflects an emerging emphasis on the binaries of InN and AlN. The major thrust here is the topical development of thin-film growth, bulk growth techniques, methods to cover the full ternary and quaternary alloy ranges toward InN and AlN and their characterization; strategies for structural defect reduction and their characterization; ways to better control p-type doping and its characterization; device and defect physics, including polarization effects; physics of surfaces and interfaces; and device processing techniques. In addition, advances in MBE devices, high-power electronics, RF performance of electronics, UV emitters, high-efficiency light emitters, photo and chemical sensors, as well as new applications within the group-III nitrides, are also covered. The book captures the current status of this field and will be useful for researchers working with group-III nitrides, as well as for students who seek entry into this subject.

Author : Colleen Bettles
Publisher : Elsevier
Page : 478 pages
File Size : 12,34 MB
Release : 2012-04-25
Category : Technology & Engineering
ISBN : 0857093843

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This important book summarises the wealth of recent research on our understanding of process-property relationships in wrought magnesium alloys and the way this understanding can be used to develop a new generation of alloys for high-performance applications. After an introductory overview of current developments in wrought magnesium alloys, part one reviews fundamental aspects of deformation behaviour. These chapters are the building blocks for the optimisation of processing steps covered in part two, which discusses casting, extrusion, rolling and forging technologies. The concluding chapters cover applications of wrought magnesium alloys in automotive and biomedical engineering. With its distinguished editors, and drawing on the work of leading experts in the field, Advances in wrought magnesium alloys is a standard reference for those researching, manufacturing and using these alloys. Summarises recent research on our understanding of process-property relationships in wrought magnesium alloys Discusses the way this understanding can be used to develop a new generation of alloys for high-performance applications Reviews casting, extrusion, rolling and forging technologies, fundamental aspects of deformation behaviour, and applications of wrought magnesium alloys in automotive and biomedical engineering

Author : Krishnan K. Sankaran
Publisher : Elsevier
Page : 508 pages
File Size : 23,26 MB
Release : 2017-06-14
Category : Technology & Engineering
ISBN : 0128120258

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Metallurgy and Design of Alloys with Hierarchical Microstructures covers the fundamentals of processing-microstructure-property relationships and how multiple properties are balanced and optimized in materials with hierarchical microstructures widely used in critical applications. The discussion is based principally on metallic materials used in aircraft structures; however, because they have sufficiently diverse microstructures, the underlying principles can easily be extended to other materials systems. With the increasing microstructural complexity of structural materials, it is important for students, academic researchers and practicing engineers to possess the knowledge of how materials are optimized and how they will behave in service. The book integrates aspects of computational materials science, physical metallurgy, alloy design, process design, and structure-properties relationships, in a manner not done before. It fills a knowledge gap in the interrelationships of multiple microstructural and deformation mechanisms by applying the concepts and tools of designing microstructures for achieving combinations of engineering properties—such as strength, corrosion resistance, durability and damage tolerance in multi-component materials—used for critical structural applications. Discusses the science behind the properties and performance of advanced metallic materials Provides for the efficient design of materials and processes to satisfy targeted performance in materials and structures Enables the selection and development of new alloys for specific applications based upon evaluation of their microstructure as illustrated in this work

Author : A.K. Suri
Publisher : Routledge
Page : 272 pages
File Size : 35,50 MB
Release : 2017-11-13
Category : Science
ISBN : 1351448978

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The growth and development witnessed today in modern science, engineering, and technology owes a heavy debt to the rare, refractory, and reactive metals group, of which niobium is a member. Extractive Metallurgy of Niobium presents a vivid account of the metal through its comprehensive discussions of properties and applications, resources and resource processing, chemical processing and compound preparation, metal extraction, and refining and consolidation. Typical flow sheets adopted in some leading niobium-producing countries for the beneficiation of various niobium sources are presented, and various chemical processes for producing pure forms of niobium intermediates such as chloride, fluoride, and oxide are discussed. The book also explains how to liberate the metal from its intermediates and describes the physico-chemical principles involved. It is an excellent reference for chemical metallurgists, hydrometallurgists, extraction and process metallurgists, and minerals processors. It is also valuable to a wide variety of scientists, engineers, technologists, and students interested in the topic.

Author : Karl U. Kainer
Publisher : John Wiley & Sons
Page : 293 pages
File Size : 25,66 MB
Release : 2006-03-06
Category : Technology & Engineering
ISBN : 3527605967

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The need for light-weight materials, especially in the automobile industry, created renewed interest in innovative applications of magnesium materials. This demand has resulted in increased research and development activity in companies and research institutes in order to achieve an improved property profile and better choice of alloy systems. Here, development trends and application potential in different fields like the automotive industry and communication technology are discussed in an interdisciplinary framework.