Molecular dynamics simulations of the interaction between a screw dislocation and a 3.5nm diameter body-centred cubic Cu precipitate in body-centred cubic Fe were performed in the twinning and anti-twinning direction between 10 and 400K. The results indicated a significant temperature dependence in the anti-twinning direction, whereby the screw dislocation bypasses the Cu precipitate by Orowan looping below 200K, but shears the precipitate above 300K. The transition in interaction mechanism was caused by a screw dislocation assisted martensitic transformation of the Cu precipitate, which significantly diminishes above 300K. The screw dislocation shears the precipitate at all temperatures between 10 and 400K in the twinning direction. Thus, transformation of the precipitate induces additional precipitate strengthening below 200K in the anti-twinning direction, which drastically decreased with increasing temperature above 300K.

Atomistic Study of Temperature Dependence of Interaction between Screw Dislocation and Nanosized BCC Cu Precipitate in BCC Fe. J.H.Shim, D.I.Kim, W.S.Jung, Y.W.Cho, K.T.Hong, B.D.Wirth: Journal of Applied Physics, 2008, 104[8], 083523