The microstructure of Mg-Al-Ca alloys consists of a hard intra- and intergranular eutectic Laves phase network embedded in a soft α-Mg matrix. For such heterogeneous microstructures, the mechanical response and co-deformation of both phases under external load are not yet fully understood. We therefore used nano- and microindentation in combination with electron microscopy to study the deformation behaviour of an Mg-3.68Al-3.8Ca alloy.

We found that the hardness of the Mg₂Ca phase was significantly larger than the α-Mg phase and stays constant within the measured temperature range. The strain rate sensitivity of the softer α-Mg phase and of the interfaces increased while activation volume decreased with temperature. The creep deformation of the Mg₂Ca Laves phase was significantly lower than the α-Mg phase at 170 °C. Moreover, the deformation zone around and below microindents was dependant on the matrix orientation and was influenced by the presence of Laves phases. Most importantly, slip transfer from the α-Mg phase to the (Mg,Al)₂Ca Laves phase occurred, carried by the basal planes. Based on the observed orientation relationship and active slip systems, a slip transfer mechanism from the soft α-Mg phase to the hard Laves phase is proposed. Further, we present implications for future alloy design strategies.

Mg-Al-Ca 合金的微观结构由嵌入在软 α-Mg 基体中的硬质晶内和晶间共晶 Laves 相网络组成。对于这种异质微观结构，外载荷作用下两相的机械响应和共变形尚不完全清楚。因此，我们使用纳米和微压痕结合电子显微镜来研究 Mg-3.68Al-3.8Ca 合金的变形行为。

我们发现 Mg ₂ Ca 相的硬度明显大于 α-Mg 相，并且在测量温度范围内保持恒定。较软的 α-Mg 相和界面的应变速率敏感性增加，而活化体积随温度降低。在 170 °C时，Mg ₂ Ca Laves 相的蠕变变形明显低于 α-Mg 相。此外，微压痕周围和下方的变形区取决于基体方向，并受 Laves 相的影响。最重要的是，滑移从 α-Mg 相转移到 (Mg,Al) ₂Ca Laves 相发生，由基面携带。基于观察到的取向关系和主动滑移系统，提出了从软α-Mg相到硬Laves相的滑移转移机制。此外，我们提出了对未来合金设计策略的影响。