Laves相中共格Shockley位错的热激活本质
Thermally activated nature of synchro-Shockley dislocations in Laves phases
AI总结：
本研究针对Laves相中共格Shockley位错运动热激活本质不明的问题，探究不同应变水平下的跃迁机制，将事件分为剪切敏感与不敏感两类，明确了热激活对其运动的关键作用。
摘要：
共格Shockley位错作为带状位错，是Laves相在高温下塑性变形的主要载体。其运动由扭折对形核、扩展等局域跃迁事件构成，这类事件激活体积较小，推测会使Peierls应力表现出明显的温度与应变速率依赖性。但目前人们对共格Shockley位错运动的热激活本质尚未完全明晰。本研究探究了不同剪切应变与正应变水平下共格Shockley位错运动的跃迁机制，发现位错运动的跃迁过程可分为剪切敏感型与剪切不敏感型事件：外加剪切应变会降低剪切敏感型事件的能垒，而剪切不敏感型事件的激活离不开热辅助，这表明低温下共格Shockley位错的运动受到抑制。
英文摘要：
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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