Mg-Y-Si合金制备及组织分析

在热力学计算分析的基础上,用SiO2粉末和纯镁制备Mg-3%Si(质量分数)中间合金,并用光电直读光谱仪测定制备的中间合金Si的含量,表明其含量稳定且可控。用普通重力铸造法制备了Mg-2Y-1Si合金和Mg-3Y-1Si合金,该合金的铸态组织由α-Mg相、(α-Mg+Mg2Si)共晶组织以及在晶内、枝晶间少量分布的点状Mg24Y5相组成。通过对α-Mg晶格常数的计算及通过原子尺寸、电负性、晶体结构的对比,证明Y固溶在基体中形成固溶体。研究表明,Y通过依附在生长界面前沿,有效抑制基体的生长速度,细化基体组织,且随着Y添加量的增加,细化效果更加明显。

Preparation and microstructure analysis of Mg-Y-Si alloy

Based on thermodynamic calculation and analysis,the Mg-3%Si(mass fraction) intermediate alloy was prepared with SiO2 powders and Mg.The Si content of the prepared intermediate alloy was determined with Photoelectricity Direct-Reading Spectrometer.The results show that the Si content of the prepared intermediate alloy is stable and controllable.Mg-2Y-1Si and Mg-3Y-2Si alloy were prepared by general gravity casting.The microstructure of as-cast Mg-2Y-1Si and Mg-3Y-1Si alloy consists of α-Mg phase,α-Mg+Mg2Si eutectic structure and few globular shape Mg24Y5 phases within grain and dendrites.The results indicate that Y is formed into solid solution,which is proved by calculating lattice constants and comparing atomic size factor,electronegativity difference,and the crystal structure.The study shows that Y effectively inhibits growth rate of matrix and refines matrix structures.And with the increasing of Y addition,the refined results become more obviously.