Molecular dynamics simulation of temperature dependence of dislocation behavior in fcc Ni single crystal under tensile condition

A molecular dynamics (MD) simulation of plastic deformation under a uniaxia l tensile strain condition for fee Ni single crystals is performed in order to clarify the temperature dependence of the edge dislocation behavior. Si mulations are performed for the temperature range from 77 to 1200 K using F innis-Sinclair-type potentials. An edge dislocation first forms at the surf ace and propagates inside of the crystal on the (111) planes in the (112) d irection. The temperature dependence of the simulated Young's modulus is qu ite similar to the experimental results. The transverse sound velocity is e stimated from the simulated elastic constants at each temperature. Below 60 0 K: the dislocation speed reaches up to 70% of the transverse sound veloci ty. The dislocation speed decreases with increasing temperature linearly ab ove 600 K. Dislocations at elevated temperature propagate under lower stres s than at room temperature. The extrapolated dislocation speed becomes zero at 1200 K. At this temperature, no dislocations are observed in the presen t simulation system. The temperature dependence of macroscopic deformation behavior and the possibility of the existence of supersonic dislocations ar e discussed.