Molecular dynamics simulations of nanocrystalline Ta during uniaxial tensile deformation process

Using molecular dynamics simulations, the microstructure evolution of nanocrystalline Ta under uniaxial tensile loading is investigated. The results show that stress-induced phase transitions from BCC to FCC and HCP structures may take place during the deformation process. The maximum of the fraction of FCC atoms varies with the tensile strength linearly, by which we can find a critical stress when the phase transition takes place. The higher the strain rate is, the later the phase transition occurs. Intergranular fracture is also found during the deformation process. Crack-formation strain is influenced not by the mean grain size, but also by the strain rate and the simulation temperature.