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学术讲座——Non-conventional Phase Transformation Pathways in Titanium Alloys
发布日期:2017-10-19 10:31:45 阅读次数:347

题目/Title 2:Integrated Experimental and Computational Studies of Non-conventional Phase Transformation Pathways in Titanium Alloys

报告人/Speaker:郑雨枫,博士

俄亥俄州立大学材料科学与工程系,材料加速熟化中心,电子显微分析中心

报告人工作单位/AffiliationThe Ohio State University, Department of Materials Science and Engineering 

日期/Date 20171020(星期五)Oct. 20 (Friday), 201710:30-11:30 AM

联系人/Contact冯强 教授      lufan@xs.ustb.edu.cn

报告地点/Location北京科技大学主楼 353 / 353 Main Building, USTB


报告摘要/Abstract

The precipitation of hcp alpha phase in bcc beta phase matrix is critical for titanium alloys due to its significant influence on mechanical properties. The nucleation of alpha phase can be affected strongly by the compositional and/or structural instabilities within the beta matrix and so may follow non-conventional transformation pathways. In this research, the pathways for refined and super-refined intragranular precipitation of the alpha phase in Ti-5Al-5Mo-5V-3Cr (Ti-5553) were studied coupling advanced modern characterization techniques and powerful computational simulation. Experimental results indicate clearly that during the as-quenched condition Ti-5553 being heated up rapidly to the ultimate aging temperature (600°C), refined alpha microstructure is produced in beta matrix by pseudo-spinodal decomposition mechanism in which large number of solute lean regions formed by thermal compositional fluctuation act as favorable sites of alpha precipitation. While on the other hand, during as-quenched condition Ti-5553 being heated up slowly, the pre-formed large number of nano-scale isothermal omega phase particles can assist subsequent super-refined alpha precipitation. Computational simulation using phase field modeling based on structural and compositional information obtained from experiment shows that the presence of such fine scale compositional and/or structural instabilities due to pre-formed solute lean region or the omega phase particles can modify the compositional and stress field in the parent beta matrix and therefore provide an extra driving force, and nucleation site, for alpha precipitation. A detailed understanding of non-transformation pathway controlling refined and super-refined alpha microstructure in Ti-5553 will be described.




作者简介/Speaker’s short biography

郑雨枫博士现任美国俄亥俄州立大学材料科学与工程系,材料加速熟化中心,以及电子显微分析中心科研工程师。他于2007年在中国科学技术大学物理系取得应用物理学学士学位,2010年及2013年在俄亥俄州立大学材料科学与工程系取得材料学硕士及博士学位。

郑雨枫博士致力于钛合金固态相变行为机制的多尺度电子显微学及计算机模拟理论研究,特别针对高强度双相Beta钛合金,开展了针对固态相变初期纳米尺度结构与成分不稳定性及该不稳定性对相变机制的影响的系统研究。同时参与完成了多项集成计算材料科学(ICME)在加速钛合金发展中的应用,以及材料基因组低弹性模量钛合金数据库建设等研究项目。

郑雨枫博士在Acta MaterialiaScripta Materilia的物理冶金学杂志上发表多篇文章,其中2篇文章被Web of Science列为学科内高引用文章,并在TMSMS&T,世界钛合金大会,及世界固态相变大会中做相关报告20余次,被世界固态相变大会(2015年)授予杰出青年学者候选人奖。郑雨枫博士作为TMS相转变及组织结构演变委员会成员,多次负责组织与主持TMSMS&T年会中固态相变分会。


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