Modelling the Tensile Instability of Nanocrystalline Metallic Materials

나노금속재료의 인장불안정에 대한 모델링

In this paper, the effect of grain refinement on room temperature ductility of copper was addressed. Recent experimental results have shown that this material, as well as a number of other single-phase metals that are ductile when coarse-grained, loose their ductility with decreasing grain size in the sub micrometer range. A recently developed model in which such materials are considered as effectively two-phase ones (with the grain boundaries treated as a linearly viscous second phase) was applied to analyze stability of Cu against ductile necking. As a basis, Hart's stability analysis that accounts for strain rate sensitivity effects was used. The results confirm the observed trend for reduction of ductility with decreasing grain size. The model can be applied to predicting the grain size dependence of ductility of other metallic materials as well.