Room-temperature solid solution softening in Fe-V binary system

Molecular dynamics simulations of the glide of an edge dislocation in the bcc matrix of Fe-V alloys were performed to investigate the room-temperature solid solution softening by V atoms. For this purpose, the glide velocity of an edge dislocation was calculated as a function of V concentration under the shear stresses of 100-300MPa using the Fe-V cross-potential constructed newly in the present study. Whereas the solid solution hardening occurred as the V concentration is less than 0.13 at% or more than 0.5 at%, the room-temperature solid solution softening was observed in Fe-(0.13-0.5) at% V alloys. The solid solution softening occurring in Fe-(0.13-0.5) at% V alloys was caused by the accelerated growth velocity of kinks by solute V atoms. The increase in kink velocity happened when the interatomic distance between solute V atoms was similar to the length of dislocation kinks.