Mechanical properties of amorphous metal with dispersed nanocrystalline particles (the effects of crystal distribution and a maximum strength studied by molecular dynamics simulations)

Abstract

The mechanical properties of amorphous metals and metallic glasses are remarkably changed by precipitated nanocrystalline particles. It is important to clarify the relationship between the internal structures and the mechanical properties to obtain a definite guide for designing new materials composed of amorphous and crystal phase. In this study, molecular dynamics simulations of tensile deformation of the amorphous metals with dispersed nanocrystalline particles were performed in order to reveal the effects of crystal distribution on the strength. The shifted Lennard-Jones potential whose potential parametes were defined based on Inoue's three basic principles was used as an interatomic potential. Here we show the material is effectively strengthened when the contacts between crystal particles are few. The phenomenon mainly attributes to the role of grain boundaries as a dislocation source. We also present that a maximum flow stress appears when the crystal volume fraction is high, whereas the grain boundary fraction is low. The maximum flow stress is higher than that of nano-sized polycrsystalline structure.