报告题目: |
Strengthening metals by means of nano-scale twins |
报告人: |
卢柯 |
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院士 中科院金属所/沈阳材料科学国家实验室
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报告时间: |
2009-03-12 16:00 |
报告地点: |
郑裕彤讲堂 |
主办单位: |
物理系 |
简介: |
报告摘要：Strengthening materials traditionally involves controlled creation of internal defects and boundaries so as to obstruct dislocation motion. Conventional approaches to strengthen metals include alloying, grain refinement, plastic straining, dispersion or precipitation. These strengthening strategies, however, invariably compromise ductility, the ability of the material to deform, stretch or change shape permanently without breaking. In the present talk, a recently-developed novel strengthening approach for metals and alloys will be introduced, i.e., nano-twin strengthening. By introducing a high density of nano-scale coherent twin boundaries in a polycrystalline copper, its strength can be elevated by one order of magnitude. At the same time, a considerable tensile plasticity and work-hardening rate are maintained as well. Synthesis and mechanical properties of the nano-twinned Cu samples will be systematically introduced with experimental observations and atomistic simulation results. Tensile strength, ductility, work-hardening, strain rate sensitivity, as well as the twin boundary density effect on these properties will be demonstrated in comparison with those in conventional nanocrystalline Cu samples. Strengthening mechanism of nano-scale twins in metals will be analyzed in terms of interaction between dislocations and twin boundaries. Perspectives will be presented on potential applications of nano-twin strengthening for improving failure tolerance, electrical conductivity, and resistance to electromigration.
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