ABSTRACT The comparative studies of grain refinement of commercial purity Mg by CaO/Ca addition have been investigated by using TP-1 tests, optical microscope, XRD characterisation and TEM (STEM) observation along with EDX analysis. Experimental results showed that Ca/CaO addition significantly refines the grain structure of commercial purity Mg. Compared with Ca addition, CaO exhibits finer grain size and the average grain size remains invariable with further CaO addition. CaO addition is readily reduced to Ca by Mg melt and forms Mg2Ca on the surface of MgO particles. First-principle calculations were used to understand the nucleation of Mg2Ca layer by a coherent interface model calculating the work of adhesion and the interface energy between Mg2Ca and α-Mg. The combination of experiments and calculations showed that the formation of Mg2Ca layer on MgO facilitates the nucleation of α-Mg and then refines the grain structure by Ca or CaO addition.

中文翻译：

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CaO和Ca添加对商品纯Mg晶粒细化的对比研究

摘要 通过使用 TP-1 测试、光学显微镜、XRD 表征和 TEM (STEM) 观察以及 EDX 分析，研究了通过 CaO/Ca 添加对商业纯镁的晶粒细化的比较研究。实验结果表明，Ca/CaO 的添加显着细化了商业纯镁的晶粒结构。与 Ca 的添加相比，CaO 的晶粒尺寸更细，平均晶粒尺寸随着 CaO 的进一步添加而保持不变。添加的 CaO 很容易被 Mg 熔体还原为 Ca，并在 MgO 颗粒表面形成 Mg2Ca。通过计算粘附功和 Mg2Ca 和 α-Mg 之间的界面能的相干界面模型，使用第一性原理计算来理解 Mg2Ca 层的成核。