The unveiling of temperature effects on the deformation behaviors of wrought magnesium (Mg) alloys is beneficial for optimizing the hot forming parameters of these alloys with limited room temperature (RT) formability. In the present work, we performed nanoindentations on individual grains of textured wrought AZ31 alloy along the normal direction (ND) from RT to 300 °C to investigate the intrinsic non-basal dislocation behaviors at various temperatures. Interestingly, we observed abnormally enhanced nanoindentation displacement bursts (pop-ins) at elevated temperatures ranging from 150 to 250 °C, which is beyond the general scenario that higher temperatures typically result in smoother plastic flow. The bursts exhibited Gaussian-like statistics, which differ from the well-reported bursts with power-law size distributions resulting from the destruction of jammed dislocation configurations. Through transmission electron microscopy (TEM) examination of the microstructure beneath the indentation just after the burst, we found that the abnormal displacement bursts originated from the heterogeneous nucleation of prismatic screw 〈〉 dislocations due to the exhaustion of dislocation sources within the specified temperature range.

中文翻译：

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AZ31镁合金纳米压痕过程中高温下异常增强的位移爆发


温度对变形镁（Mg）合金变形行为的影响的揭示有利于优化这些具有有限室温（RT）成形性的合金的热成形参数。在目前的工作中，我们在 RT 至 300 °C 的范围内沿法线方向 (ND) 对织构变形 AZ31 合金的单个晶粒进行纳米压痕，以研究不同温度下的固有非基本位错行为。有趣的是，我们在 150 至 250 °C 的高温下观察到异常增强的纳米压痕位移爆发（弹出），这超出了较高温度通常会导致更平滑的塑料流动的一般情况。这些爆发表现出类似高斯的统计数据，这与由于干扰位错构型破坏而产生的幂律尺寸分布的爆发不同。通过透射电子显微镜（TEM）对爆发后压痕下方的微观结构进行观察，我们发现异常位移爆发源于在指定温度范围内位错源耗尽而导致的棱柱螺<>位错的异质形核。