Thermally activated nature of synchro-Shockley dislocations in Laves phases

ZC Xie and D Chauraud and A Atila and E Bitzek and S Korte-Kerzel and J Guénolé, SCRIPTA MATERIALIA, 235, 115588 (2023).

DOI: 10.1016/j.scriptamat.2023.115588

Synchro-Shockley dislocations, as zonal dislocation, are the major carrier of plasticity in Laves phases at high temperatures. The motion of synchro-Shockley dislocations is composed of localized transition events, such as kink-pair nucleation and propagation, which possess small activation volumes, presumably leading to sensitive temperature and strain rate dependence on the Peierls stress. However, the thermally activated nature of synchro-Shockley dislocation motion is not fully understood so far. In this study, the transition mechanisms of the motion of synchro-Shockley dislocations at different shear and normal strain levels are studied. The transition processes of dislocation motion can be divided into shear-sensitive and-insensitive events. The external shear strain lowers the energy barriers of shear-sensitive events. Thermal assistance is indispensable in activating shear- insensitive events, implying that the motion of synchro-Shockley dislocations is prohibited at low temperatures.

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