报告题目：

Strength Statistics of Single Crystals and Metallic Glasses under Small Stressed Volumes  

报告人:                    Prof.  Yanfei Gao

                                   University of Tennessee

时间：2018年7月4日(周三)  9:00

地点：中科院力学所1号楼344室

报告摘要：

The plastic deformation of crystalline and amorphous metals/alloys shows a general trend of ‘‘smaller is stronger”. However, most studies have been focused on finding and reasoning the scaling slope or exponent in the logarithmic plot of strength versus size. Here we show that the universal picture should rather be the thermally activated nucleation mechanisms in small stressed volume, the stochastic behavior as to find the weakest links in intermediate sizes of the stressed volume, and the convolution of these two mechanisms with respect to variables such as indenter radius in nanoindentation pop-in, crystallographic orientation, pre-strain level, sample length as in uniaxial tests, and others. Experiments that cover the entire spectrum of length scales and a unified model that treats both thermal activation and spatial stochasticity have discovered new perspectives in understanding and correlating the strength statistics in a vast of observations in nanoindentation, micro-pillar compression, and fiber/whisker tension tests of single crystals and metallic glasses.

报告人简介：

Dr. Gao is a Professor at Department of Materials Science and Engineering, University of Tennessee (UT), USA. He received his BS degree in Engineering Mechanics from Tsinghua University in 1999, and PhD from Princeton (advised by Prof. Zhigang Suo) in 2003. He was a post-doctoral research associate at Brown University (advised by Profs. Allan Bower and Kyung-Suk Kim) in 2003-2005. Since 2005, he is a faculty at UT and also a joint research staff member at Oak Ridge National Laboratory. His research activities have been focusing on deformation and failure of advanced structural materials such as metallic glasses, superalloys, high entropy alloys, and structural ceramics. He has published more than 120 journal papers, many of which are in Journal of the Mechanics and Physics of Solids and Acta Materialia.