题目：Deformation Twinning at Different Length Scale

　　报告人：Dr. Mingxin HUANG (黄明欣)（香港大学机械工程系）

　　时间：8月18日（周一） 10:00-11:30

　　地点：李薰楼468会议室

　　欢迎参加！

Deformation Twinning at Different Length Scale

Mingxin HUANG (黄明欣)

Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China

Email: mxhuang@hku.hk

　　Abstract

　　Twinning Induced Plasticity (TWIP) steels recently attract tremendous research attentions from both academia and industry due to their excellent mechanical properties, namely, high ultimate tensile strength and high ductility. The first part of the talk presents a dislocation-based model to explain the work hardening behaviour of bulk samples of TWIP steels. The model includes the effect of chemical compositions. The strength of twin boundary changes with chemical composition, resulting in different number of dislocations piled up at the twin boundary. Larger number of dislocations piled up at the twin boundary induces a higher back stress (i.e., kinematic hardening) and therefore an increase of work hardening rate. The model predictions are in good agreement with experimental results in a wide range of Fe-Mn-C TWIP steels.

　　The second part of the present talk discusses the deformation mechanism of TWIP steels in submicon and micron samples. Mechanical twins are found to nucleate and grow in both pillars under compression. The twin thickness ranges from nanometres to micrometres, and nucleation and growth are due to emission and glide of partial dislocations from the pillar surface as confirmed by transmission electron microscopy investigations. A new physical model is proposed to describe the twinning kinetics in micron-sized samples.

黄明欣博士简介

　　香港大学机械工程系助理教授，博士生导师

　　个人主页：http://web.hku.hk/~mxhuang

　　黄明欣博士分别于2002年和2004年从上海交通大学获得工程力学学士学位和固体力学硕士学位。硕士毕业之后，他前往荷兰代尔夫特理工大学 (TU Delft)攻读博士学位，师从国际著名钢铁材料专家荷兰皇家科学院院士Sybrand Van Der Zwaag 教授。从2008年至2010年，在ArcelorMittal (安赛乐米塔尔)位于法国的全球研发总部任研究工程师，主要从事新型高强度汽车钢的研发工作。在2010年，他辞去安赛乐米塔尔的研究员职位，应聘为香港大学机械工程系的助理教授，目前在香港大学机械工程系独立带领一个金属材料课题组。

　　黄明欣博士现在的研究工作包含 (1)汽车用先进高强度钢 (AHSS)， (2) 纳米结构钢，(3) 金属力学性能与微观结构的关系等领域。黄明欣博士以第一作者或者通讯作者在Acta Materialia和Scripta Materialia等国际期刊上发表SCI论文约40篇, H-index 为10。多次在国际会议做邀请报告。目前主持香港研究资助局资助项目二项，国家自然科学基金青年基金一项，香港政府科技署项目一项，法国ArcelorMittal公司资助项目两项，通用汽车中国研究院资助项目一项，鞍钢研究院资助项目一项，累计科研经费接近5百万港币，具备相对丰富的基础研究及工程材料研发经验。