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

通过特殊的不变形技术对金属进行冷加工，使其表现出不同寻常的强度和超塑性等力学性能。在本研究中，我们通过电阻率和动态弹性模量测量等各种技术研究了变形引起的缺陷的类型和密度及其热稳定性。研究发现，在高纯度的材料中，晶粒尺寸的减小效率较低，这表明杂质对制备超细晶粒金属是有利的。结果表明，杂质有助于缺陷的热稳定性和细晶组织的形成。

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.