High-performance binary Mg–Ca alloys are engineered by intelligent alloying and thermo-mechanical processing using hot-extrusion. With Ca-alloying contents as low as 0.2-0.6 wt.%, remarkable room-temperature tensile properties are obtained with tensile strength values as high as 380–420 MPa, or ductility values reaching a maximum of 36 %. By means of multiscale structural and chemical analysis using electron microscopy and energy dispersive X-ray spectroscopy, we show that multimodal strengthening mechanisms can be activated by modifying the spatial distribution of Ca as secondary phase. Our results indicate that strong precipitation strengthening is achieved when MgCa phase particles are dispersed within the grains. On the other hand, preferential distribution of the MgCa precipitates along grain boundaries imparts substantial grain-boundary strengthening by the Hall-Petch effect. Apart from secondary-phase precipitation, the role of Ca as solute atoms is paramount in promoting homogeneous deformation. The presence of Ca directly alters the intrinsic stacking fault energies and modifies the cross-slip energy barriers such that the slip-transition probability from pyramidal-to-basal and vice-versa becomes comparable. Both effects ensure competitive activation of basal and non-basal slip, thereby reducing the mechanical anisotropy. The mechanical performance in the current work, when compared to earlier reported studies of Mg alloys with similar or higher alloying content, shows a 2 to 10-fold increase in tensile strength without compromising ductility.

中文翻译：

---

高性能超贫可生物降解镁钙合金及其加工指南


高性能二元镁钙合金是通过智能合金化和热挤压热机械加工而设计的。当钙合金含量低至 0.2-0.6 wt.% 时，即可获得显着的室温拉伸性能，拉伸强度值高达 380-420 MPa，延展性值最高可达 36%。通过使用电子显微镜和能量色散 X 射线光谱进行多尺度结构和化学分析，我们表明可以通过改变第二相 Ca 的空间分布来激活多峰强化机制。我们的结果表明，当 MgCa 相颗粒分散在晶粒内时，可以实现强沉淀强化。另一方面，MgCa 析出物沿晶界的优先分布通过 Hall-Petch 效应赋予显着的晶界强化。除了第二相沉淀之外，Ca 作为溶质原子的作用对于促进均匀变形至关重要。 Ca 的存在直接改变了固有的堆垛层错能量并修改了横向滑移能垒，使得从金字塔到基底的滑移跃迁概率变得相当，反之亦然。这两种效应都确保了基底滑移和非基底滑移的竞争性激活，从而降低了机械各向异性。与早期报道的具有相似或更高合金含量的镁合金的研究相比，当前工作中的机械性能表明，拉伸强度增加了 2 至 10 倍，且不影响延展性。