Molecular dynamics study of tension-compression asymmetry of nanocrystal α-Ti with stacking fault

Abstract

Molecular dynamics simulations are performed to investigate the effect of stacking fault (SF) boundary, loading condition and temperature on the mechanical behaviour of nanocrystalline titanium. The results indicate that the yield stress and flow stress present tension-compression asymmetry. The asymmetry is due to the different deformation mechanisms: formation of basal/prismatic interface and motion of SFs in “twin” grains in tension, and the blockage of SF boundary to the fcc-Ti phase boundary in compression. At the same time, the results show that influence of SF on yield stress and flow stress is slight under tensile loading, regardless of temperature and SF spacing. In contrary, the SF boundaries enhance the yield stress and flow stress of nanocrystal Ti under compressive loading. The general conclusions derived from present work may provide a guideline for the design of high-performance nanocrystal Ti.