Champion Yannick, Langlois Cyril, Guérin-Mailly Sandrine, Langlois Patrick, Bonnentien Jean-Louis, Hytch Martin J
Centre d'Etudes de Chimie Métallurgique-CNRS, 15 rue Georges Urbain, 94407 Vitry-sur-Seine, France.
Science. 2003 Apr 11;300(5617):310-1. doi: 10.1126/science.1081042.
Ductile metals and alloys undergo plastic yielding at room temperature, during which they exhibit work-hardening and the generation of surface instabilities that lead to necking and failure. We show that pure nanocrystalline copper behaves differently, displaying near-perfect elastoplastic behavior characterized by Newtonian flow and the absence of both work-hardening and neck formation. We observed this behavior in tensile tests on fully dense large-scale bulk nanocrystalline samples. The experimental results further our understanding of the unique mechanical properties of nanocrystalline materials and also provide a basis for commercial technologies for the plastic (and superplastic) formation of such materials.
韧性金属和合金在室温下会发生塑性屈服，在此过程中它们会表现出加工硬化以及导致颈缩和失效的表面不稳定性。我们发现，纯纳米晶铜的行为有所不同，表现出近乎完美的弹塑性行为，其特征为牛顿流体流动，且不存在加工硬化和颈缩现象。我们在对完全致密的大规模块状纳米晶样品进行的拉伸试验中观察到了这种行为。这些实验结果加深了我们对纳米晶材料独特力学性能的理解，也为这类材料的塑性（和超塑性）成型的商业技术提供了基础。
