Mechanism of discontinuous precipitation (DP) in AZ80 alloy was investigated by phase-orientation correlated characterization. The results show DPs nucleate by turning the original grain boundaries (GBs) as reaction front (RF), and further driving the RF to realize their growth. The DPs regions retained the same orientations as their parent grains. The misorientation angle and rotation axis of RFs had strong influence on DPs nucleation. The low-angle GBs, twin boundaries (TBs) and the GBs with specific misorientation axis which are known as low energy and low mobility GBs can hardly initiate DPs. In addition, the TBs had a strong ability to inhibit the growth of DPs, but it should be noticed that the growth of DPs cannot be totally inhibited by TBs. DPs can engulf the twins when the growth direction is approximately parallel to the long axis of TBs. The inhibition behavior is related to the distribution of Al solute atoms near the RF, boundary interactions of the TBs and twin tips with the RF, and the morphology of the continuous precipitations within the twins.

中文翻译：

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晶粒和孪晶界对 Mg-Al 合金中 Mg17Al12 相不连续析出的影响


通过相取向相关表征研究了 AZ80 合金中不连续析出 （DP） 的机理。结果表明，DPs 通过将原始晶界 （GB） 作为反应前沿 （RF） 来成核，并进一步驱动 RF 实现其生长。DP 区域保持与其父颗粒相同的方向。RFs 的取向差角和旋转轴对 DPs 成核有很大影响。低角度 GB、双边界 （TBs） 和具有特定取向误差轴的 GBs，被称为低能量和低迁移率 GBs，几乎不能引发 DPs。此外，TBs 具有很强的抑制 DPs 生长的能力，但需要注意的是，TB 不能完全抑制 DPs 的生长。当生长方向大致平行于 TBs 的长轴时，DPs 可以吞噬双胞胎。抑制行为与 RF 附近 Al 溶质原子的分布、TB 和双胞胎尖端与 RF 的边界相互作用以及双胞胎内连续沉淀的形态有关。