冷却方式对Mg-Nd-Pr合金的显微组织与物相构成的影响

Effect of Cooling Method on the Microstructure and Phase Composition of Mg-Nd-Pr Alloy

摘要:

采用不同的冷却方式获得了两种状态的Mg-Nd-Pr合金，利用电子探针、透射电子显微镜、X射线衍射分析仪等设备，系统分析了相应合金的显微组织和相结构。证明急冷的方法可以大幅度减小晶粒尺度，形成单相的过饱和α-Mg（Nd、Pr）固溶体，能够显著提高Mg-Nd-Pr合金的力学性能，Mg-Nd-Pr合金通过固溶强化能获得较高的强度。室温下Nd、Pr元素在α-Mg中的固溶度很小，缓慢冷却会导致合金元素在晶界析出，缓冷合金由α-Mg、Mg41Nd5和Mg12Pr等相组成，Mg41Nd5和Mg12Pr分布于α-Mg的晶界处，同时在α-Mg晶粒内部产生孪晶。

Abstract:

Two Mg-Nd-Pr alloys were prepared adopting different cooling methods, and the microstructural characteristics and phase structure of both alloys were examined by transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that the crystalline grain size is decreased greatly under the condition of melt-spin, the supersaturated α-Mg solid solution is developed, and the mechanical properties of Mg-Nd-Pr alloy are increased remarkably. The alloying elements will precipitate along the grain boundaries in a state of slow cooling owing to lower solubility for Nd, Pr in α-Mg phase at room temperature. The phase composition of such alloy includes α-Mg, Mg41Nd5 and Mg12Pr. Mg41Nd5 and Mg12Pr are distributed in the grain boundaries. At the same time, many twins within the grains are observed.