VW63Z铸造镁稀土合金回炉料遗传性及晶粒细化特征研究

Heredity and Grain Refinement Characteristics of Mg-RE Cast Alloy Scrap Returns

铸造镁稀土合金因其密度低、比强度高、高温强度高等优势已在航空航天领域得到广泛应用,然而晶粒细化程度不高及高额的制备成本制约了其更广泛的应用。文中以VW63Z高强耐热铸造镁稀土合金为研究对象,分析了报废铸件、浇注系统料、重熔埚底料三种回炉料的显微组织,在三种回炉料中均发现更多的小颗粒Zr及溶解Zr。分别以比例相同的三种回炉料作为部分原材料浇注铸件,分析组织及力学性能,并进行成本对比。结果表明,使用回炉料浇注铸件不仅能够大幅降低制备成本,而且从回炉料中遗传下来的大量优质Zr对晶粒的细化效果优于常规Mg-Zr中间合金新料,并以报废铸件重熔制备的合金组织性能最优。

Cast magnesium alloys with rare-earth elements addition, so called Mg-RE alloys in short, have been widely used in the aerospace field due to their advantages of low density, high specific strength, and good high-temperature mechanical properties. However, the low degree of grain refinement and the high cost of preparation restrict their wider application. In this study, three kinds of VW63 Z high-strength heat-resistant Mg-RE cast alloy scrap returns: rejected castings, pouring system materials and remelting pot bottom materials, were utilized. The microstructure observation found that there are more small particles of Zr and dissolved Zr in the three kinds of VW63 Z alloy returns. After the castings were produced respectively using the returns mentioned above and with the addition of the same proportion, the observation of microstructure, testing of mechanical properties and the comparison of the production cost were carried out. The results show that not only has the production cost of the castings been greatly reduced due to the use of returns, but the effect of grain refinement has been improved as well duo to the fact that there exist a large amount of highquality Zr particles inherited from the scrap returns. In addition, the alloy casting produced using the rejected castings has the most fine microstructure and the best mechanical properties.