Molecular dynamics simulation of nanocrack propagation mechanism of polycrystalline titanium under tension deformation in nanoscale

Abstract

In order to explore the nanoscale mechanism of nanocrack propagation in polycrystalline titanium under tensile condition, molecular dynamics model of polycrystalline titanium was established. The propagation mechanism of nanocrack in polycrystalline titanium was analyzed under different crack locations, strain rates and temperatures. It reveals the influence of various factors on the nanocrack propagation process. It is found that the fracture mode of polycrystalline titanium at low temperature is mainly brittle cleavage, and the presence of grain boundary makes the material brittle. At room temperature, the material plasticity increases. This makes the crack tip passivate and the crack growth rate slow down. With the increase of the strain rate, the crack propagation speed decreases, which is related to the plasticity enhancement of the material under high strain rate. No matter the crack is in the grain boundary or the grain inner, it will eventually expand along the grain boundary, and the grain boundary plays a guiding role in the crack propagation direction.