ナノ結晶分散アモルファス金属の力学特性

粒子寸法効果発現についての分子動力学解析

抄録

Molecular dynamics simulations of tensile deformation of amorphous metals with dispersed nanocrystalline particles were performed in order to reveal the particle size effects on Young's modulus and the flow stress through all crystal volume fraction from 0% (amorphous) to 100% (nanocrystalline metal).The analysis model used in this research contains 32 nano-scaled crystal-particles with random orientation in a unit cell. It became clear that the Young's modulus of the nano-composite is increased as the average particle radius and the crystal volume fraction increase. On the other hand, the flow stress is not affected by the particle size when the crystal volume fraction is lower than 60%. The particle size effects appear gradually for higher crystal volume fraction models. This phenomenon is caused by an increase of the fraction of the grain boundary to the entire interface. We also demonstrate that the elastic constants can be estimated with a higher accuracy by employing a self-consistent compliance model based on the equivalent inclusion method. The Lennard-Jones potential, modified to enforce the continuity at the cut off distance, was used as an interatomic potential. The potential parametes were defined based on Inoue's three basic principles.