Quantitative analysis of crystalline defects that control anomalous properties of severely-deformed metals and investigation of their thermal stability

经过特殊形状不变变形的严重冷加工金属表现出异常的强度和超塑性等有趣的力学性能。在本研究中，我们通过测量电阻率和动态弹性模数等多种技术，研究了形变引入的缺陷的类型、密度及其热稳定性。研究发现，高纯度材料的细化效果较差，说明杂质对制备超细晶金属是有利的。同时，杂质对缺陷的热稳定性和细晶组织也有一定的贡献。

Severely cold-worked metals by special shape-invariant deformation techniques exhibit such interesting mechanical properties as unusual strength and super-plasticity. In the present research, we have studied the type and the density of the defects introduced by the deformation and their thermal stability by various techniques such as measurements of electrical resistivity and dynamic elastic modulus. It has been found that the size of crystal grains is reduced less efficiently in materials of higher purity, indicating that impurities are advantageous for preparing ultra-fine-grained metals. It also turned out that impurities contribute to the thermal stability of the defects and the fine-grained microstructure.