Grain boundary segregation in magnesium alloys and its role in controlling the microstructure and mechanical properties

镁合金中的晶界偏析及其对显微组织和力学性能的控制作用

基本信息

批准号：
394480829
负责人：
Dr.-Ing. Talal Al-Samman
金额：
--
依托单位：
Institut für Metallkunde und Metallphysik (IMM)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/394480829?language=en
关键词：
Grain boundary segregation magnesium alloys

项目摘要

Magnesium-zinc alloys containing rare earth (RE) additions exhibit enhanced cold formability owing mostly to commercially attractive weak textures developed upon recrystallization. However, it is still unclear whether the texture modification effect in these alloy systems arises primarily from single alloying elements or from their combination. Due to the complex interplay of Zn and RE the exact underlying mechanisms remain an outstanding issue. It is hypothesized that suppression of dynamic recrystallization during deformation and retardation of grain boundary motion during static recrystallization due to solute segregation effects play a key role in understanding the rare earth effect on texture. Based on a selection criterion combining large atomic size misfit with magnesium and high bulk solubility, the proposed project aims to investigate the GB segregation characteristics of several potential RE (Gd, Dy and Er) and non-RE elements, such as Ca that has a large atomic size equivalent to RE metals, and is thus expected to show the RE texture change effect. The fact that RE elements are relatively expensive and not readily available across the globe renders the investigation of Ca as a substitute for RE technologically attractive. Special attention will be given to resulting solute drag effects on altering common recrystallization and growth mechanisms requiring boundary migration, and how this affects the development of texture and microstructure during annealing. Beside the effect of single alloying elements in binary alloys, synergy effects and effects of varying the concentration ratios of RE and Zn in ternary alloys will be investigated. The work program will utilize powerful structural and chemical characterization techniques, such as 3D atom probe tomography, as well as advanced level-set modeling of anisotropic grain growth to understand the process of selective grain growth and its effect on texture formation. It is highly anticipated that the research findings of the project will lead to sound physical basis for a new alloy design concept exploiting GB segregation for tailoring the microstructure of Mg alloys during thermomechanical processing to obtain a unique combination of improved strength and ductility.

含有稀土（RE）添加的镁 - 锌合金表现出增强的冷基，主要是由于重结晶后产生的商业吸引人的弱质地。但是，目前尚不清楚这些合金系统中的纹理修饰效果是否主要来自单个合金元件或它们的组合。由于Zn和RE的复杂相互作用，确切的潜在机制仍然是一个杰出的问题。假设抑制在溶质隔离效应导致的静态重结晶期间变形和晶粒边界运动的抑制作用在理解稀土对质地的稀有效应方面起着关键作用。根据选择标准将大原子尺寸失误与镁和高体积溶解度相结合，该项目旨在研究几个潜在RE（GD，DY和ER）的GB隔离特性（GD，DY和ER）和非RE元素，例如CA，例如具有较大的原子尺寸与金属的原子尺寸相等，并且预计会显示出重新质地的效果。 RE元素相对昂贵并且在全球不易获得的事实使CA的调查是替代技术吸引力的替代品。将特别注意导致溶质阻力对改变需要边界迁移的常见再结晶和生长机制的影响，以及这如何影响退火过程中纹理和微观结构的发展。除了在二元合金中单个合金元件的影响外，还将研究RE和Zn在三元合金中变化的浓度比的协同作用和影响。该工作计划将利用强大的结构和化学表征技术，例如3D原子探针断层扫描以及各向异性谷物生长的高级水平建模，以了解选择性谷物生长的过程及其对纹理形成的影响。备受期待的是，该项目的研究结果将导致一种新的合金设计概念，利用GB隔离，以在热力学处理过程中调整MG合金的微结构，以获得改善的强度和延展性的独特组合。