2015年11月17日上午9:00，中南大学十大正规外围买球网站青年科协联合院研究生会举办的青年学术沙龙第142场在特冶楼229学术活动室顺利进行，本次学术沙龙的主讲人为来自苏黎世大学的Manfred.Roth教授。

Manfred. Roth教授今天的报告会第一部分内容主题为“High temperature materials. Processing of single crystals”。首先Roth教授介绍了高温材料实际应用中常见的蠕变现象及其典型的蠕变曲线，解释了蠕变曲线的三个阶段（初始蠕变阶段、稳态蠕变阶段和加速蠕变阶段），并以自己的滑雪鞋为例讲述了生活中存在的蠕变案例。此外Roth教授还提出了粒子强化（位错切割机制以及Orowan机制）和降低材料杨氏模量的方法，以提高金属材料蠕变抗性，并展示了典型蠕变断裂的断口形貌SEM图，分析了蠕变裂纹的发展过程以及热疲劳断裂现象。接下来Roth教授以单晶涡轮叶片为例介绍了单晶材料的应用和制备工艺，包括定向凝固发、区熔法等，列举了单晶材料的众多优点—无晶界滑移、无扩散蠕变、无晶间腐蚀、[001]方向杨氏模量低等。同时Roth教授也指出了单晶材料的一些缺点，如制作成本昂贵、材料屈服强度低等，并和在场学生讨论了单晶材料未来的发展方向。

沙龙第二部分的主题为“Fractured handle bar of a bicycle”，Roth教授以自行车车把为例，讲述了日常生活中常见的金属材料疲劳断裂现象。Roth教授针对断口SEM图像，分析了断裂表面裂纹的扩展过程，指出自行车车把的断裂一般由弯矩疲劳、冲击疲劳断裂以及应力腐蚀造成，并提出了一些改善车把材料断裂性能的方法，如采用合适的Al合金材料或Al外壁Fe芯车把材料，增加车把管壁厚等。最后Roth教授总结了今天学术沙龙的全部内容，并细心回答在场学生提出的所有问题，分享了自己在高温材料领域的一些经验和想法。

报告人简介：

Prof. Dr. Manfred Roth

Department of Materials

Swiss Federal Institute of Technology Zurich, Switzerland

Education

1981  Dr. Ing. Materials Science, University of Erlangen, Germany

1978  Dipl. Ing. Materials Science, University of Erlangen, Germany

Diploma thesis: Pore formation in pure iron during creep deformation

Professional Experience

From 2015    Consultant “Advanced Materials”

2009 to 2013  Guest-Professor at Central South University, Changsha, China

2012 to 2014  Senior Scientist, Advanced Materials and Surfaces, Swiss Federal

Laboratories for Materials Testing and Research (Empa), Dubendorf, CH

2004 to 2012  Head of the Laboratory Joining- and Interface Technology, Swiss Federal

Laboratories for Materials Testing and Research (Empa), Dubendorf, CH

1991 to 2004  Head of the Laboratory Surface- and Joining Technology, Swiss Federal

Laboratories for Materials Testing and Research (Empa), Dubendorf, CH

1985 to 1991  Head of the Laboratory Physical Metallurgy/Metallography, Swiss Federal

Laboratories for Materials Testing and Research (Empa), Dubendorf, CH

1982 – 1985   Researcher, BBC Research Center, Baden, Switzerland

- Shot-peening of gas and steam turbine blades

- Material-processing by high power lasers

- Development of a duplex steel with improved corrosion and fatigue properties

Professional Affiliations

1991 – 1998 The Swiss Association for Materials Technology, Member of the Board

Publications

More than 60 scientific/technical publications in international refereed journals; 3 patents; numerous contributions to conferences and other publications.