张统一院士赴我院做学术报告

应力学系邀请，中国科学院院士上海大学张统一教授赴天津大学机械工程学院做学术报告，欢迎老师和同学们届时踊跃参加。

报告题目：Solubility and Internal Stress in Nanograined Materials and Nanoparticles

报告时间：3月14日（下周四）下午3:30

报告地点：北洋园校区37楼北楼212会议室

摘要：

In this presentation, I report the development of a Gibbs-approach based adsorption isotherm for grain boundary (GB) segregation in nanograined (ng) polycrystals and for surface segregation in nanoparticles. The newly developed adsorption isotherm takes the advantages from both Gibbs and McLean adsorption isotherms and is able to analytically calculate the GB segregation when the activation energy for GB segregation and the solute concentration in the solid solution grains are available. The solute atoms inside GBs and grains possess different partial molar volumes, thereby generating an internal stress field, which, in turn, enhances the solute solubility inside grains. For an open system, the environment serves as a solute reservoir and solute atoms can move between the ng material and the environment to maintain an equivalent chemical potential of the solute. In this circumstance, the apparent solute concentration will be greatly enhanced in an ng material in comparison to its coarse-grained counterpart. This because an ng material has a large GB volume fraction, leading to more solute atoms segregated at GBs, and a considerable increase in the lattice concentration that is boosted by the concentration-induced stress field. The Gibbs-approach based adsorption isotherm allows one to analyze simultaneously stresses, concentrations and their coupling behaviors in grains and GBs. As an example, the experimental data for the H-Pd binary system are fitted with the newly developed isotherm. The perfect fitting shows an excellent agreement between the theoretical predictions and the experimental results, and determines the GB properties as well.

张统一院士简介：

1982年获北京科技大学材料物理专业硕士学位，1985年获博士学位。1993年至2015年就职于香港科技大学，任讲师、副教授、教授、教授。现就职于上海大学，任上海大学材料基因组研究所所长，上海材料基因组研究所所长。主要研究方向为材料力学性能、微/纳米力学、材料信息学、力学信息学。曾任2013-2017年国际断裂学会(ICF)副主席，现任ICF执行委员会主任，2001年至2016年任远东及大洋洲断裂学会，获2018年何梁何利科技进步奖，2007年、1987年国家自然科学奖二等奖。2011年获中国科学院院士、2013 - 2017年任《中国科学》副主编，2018年起任主编，任《理论与应用断裂力学》(2013 -至今)杂志主编。