Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China.
Science. 2011 Mar 25;331(6024):1587-90. doi: 10.1126/science.1200177. Epub 2011 Feb 17.
Nano-grained (NG) metals are believed to be strong but intrinsically brittle: Free-standing NG metals usually exhibit a tensile uniform elongation of a few percent. When a NG copper film is confined by a coarse-grained (CG) copper substrate with a gradient grain-size transition, tensile plasticity can be achieved in the NG film where strain localization is suppressed. The gradient NG film exhibits a 10 times higher yield strength and a tensile plasticity comparable to that of the CG substrate and can sustain a tensile true strain exceeding 100% without cracking. A mechanically driven grain boundary migration process with a substantial concomitant grain growth dominates plastic deformation of the gradient NG structure. The extraordinary intrinsic plasticity of gradient NG structures offers their potential for use as advanced coatings of bulk materials.
纳米晶（NG）金属被认为是强但本质上脆性的：独立的 NG 金属通常表现出拉伸均匀伸长率的百分之几。当纳米晶铜薄膜被具有梯度晶粒尺寸过渡的粗晶（CG）铜衬底限制时，拉伸塑性可以在应变局部化被抑制的 NG 薄膜中实现。梯度 NG 薄膜表现出 10 倍更高的屈服强度和与 CG 衬底相当的拉伸塑性，并且可以在不出现裂纹的情况下承受超过 100%的拉伸真应变。具有大量伴随的晶粒长大的机械驱动晶界迁移过程主导了梯度 NG 结构的塑性变形。梯度 NG 结构的非凡固有塑性为它们作为大块材料的先进涂层的应用提供了潜力。
