Investigation of Transformation Pathways in A High Entropy Alloy with A Complex Nanoscale Microstructure Using Advanced Electron Microscopy

讲座名称: Investigation of Transformation Pathways in A High Entropy Alloy with A Complex Nanoscale Microstructure Using Advanced Electron Microscopy
讲座时间 2017-10-17
讲座地点 西二楼A102,曲江校区
讲座人 Hamish L. Fraser
讲座内容
讲座名称:Investigation of Transformation Pathways in A High Entropy Alloy with A Complex Nanoscale Microstructure Using Advanced Electron Microscopy
讲座时间:2017年10月17日,上午10:00
讲座地点:西二楼A102,曲江校区
讲座人:Prof. Hamish L. Fraser
Center for the Accelerated Maturation of Materials,
The Ohio State University
讲座内容:High-entropy alloys (HEAs) are a new class of materials garnering a great deal of attention due to their intriguing balance of properties, including high strength, ductility, and corrosion resistance. They appear to offer new pathways to lightweighting in structural applications, but to realize this potential requires considerable alloy development that will rely on integrated computational materials engineering (ICME) and a detailed knowledge of the microstructural evolution of these compositionally complex alloys. One such HEA, AlMo0.5NbTa0.5TiZr, was selected to be the basis for this characterization study due to its strength at elevated temperature, low density, and interesting nanoscale interpenetrating microstructure. HEA samples were vacuum arc-melted followed by hot isostatic pressing and homogenization at 1400 ºC for 24 hours with a furnace cool of 10 ºC/min in an inert gas atmosphere. Samples were quenched at various times during the furnace cool and have been characterized using optical, scanning electron microscopy, and aberration-corrected transmission electron microscopy. Additionally, scanning transmission electron microscopy (STEM) based tomography has been used to provide detailed 3D reconstructions of the microstructure. From this materials characterization and the heat-treatment study, the transformation pathway has been determined to involve a disorder – order transition followed by spinodal decomposition. This has been simulated using computational thermodynamics and phase field modeling.

 

 

讲座人介绍

Hamish L. Fraser教授1972年毕业于英国伯明翰大学,获得物理冶金学博士学位。1973 年加入美国伊利诺伊大学,至1989年间在伊利诺伊大学分别担任助理教授,副教授及教授。1989年至今任美国俄亥俄州“摄政王杰出学者” 和俄亥俄州立大学材料科学与工程系教授,俄亥俄州立大学材料加速熟化中心主任。Hamish L. Fraser 教授曾担任美国联合技术研究中心高级研究员,德国哥廷根大学高级洪堡访问学者,英国剑桥大学及利物浦大学客座教授。1988年起任英国伯明翰大学材料科学与工程系荣誉教授,2014年起任南非尼尔逊曼德拉大学荣誉教授,并担任澳大利亚莫纳什大学以及美国北德州大学兼职教授。

Hamish L. Fraser教授是物理冶金学领域及电子显微学领域国际著名专家,在先进电子显微技术及其应用,先进金属材料加工工艺,以及集成计算材料科学与工程等方面开展了长期系统的研究工作。Hamish L. Fraser教授是美国金属协会(ASM),美国矿物、金属和材料协会(TMS),英国材料学会、矿物和冶金协会(IOM3)及美国显微学协会会士,也是美国航空发动机材料ICME(集成计算材料工程)的创建者之一。Hamish L. Fraser教授曾任美国国防部研究与工程咨询委员、美国科学院全国材料咨询委员会委员、北约航空航天研究理事会顾问委员、英国科学与工程研究理事会材料战略工作组成员、美国Los Alamos国家实验室材料研究部评估委员会成员和剑桥大学材料系校外咨询委员会成员,并三度担任美国空军实验室科学顾问委员会成员。

Hamish L. Fraser教授在国际著名期刊发表学术论文400余篇,在国际会议及访问中受邀报告300余次,培养了超过50名博士生及30余名硕士研究生。

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