热处理对铸造Mg-4Y-3Nd-1.5Al合金显微组织和力学性能影响

Effect of heat treatment on microstructure and mechanical properties of Mg-4Y-3Nd-1.5Al alloy

摘要:

本文通过显微组织分析和力学性能测试等试验手段，研究了热处理对Mg-4Y-3Nd-1.5Al合金显微组织和力学性能的影响。结果表明:铸态合金组织中第二相主要为Mg5RE、Mg24RE5和Al2RE相，经固溶处理后（525℃×6h+550℃×12h），Mg5RE、Mg24RE5相完全溶解，Al2RE不发生溶解。Mg-4Y-3Nd-1.5Al合金具有明显的时效硬化行为，经固溶+时效处理后，合金的力学性能显著提高。经固溶（525℃×6h+550℃×12h）+峰时效（225℃×10h）处理后，Mg-4Y-3Nd-1.5Al合金屈服强度、抗拉强度和延伸率分别为:185MPa、262MPa和6.5%。获得良好的力学性能与合金中析出高密度的细小β""和β"相有关。

Abstract:

In this paper, the microstructure and mechanical properties of Mg-4Y-3Nd-1.5Al alloy with different heat treatment conditions were carried out by microstructural analysis and mechanical property testing. The experimental results show that there are Mg5RE, Mg24RE5 and Al2RE intermetallic phases in as-cast Mg-4Y-3Nd-1.5Al alloy and the Mg5RE and Mg24RE5 phases dissolved into α-Mg matrix and Al2RE phases is stable in solid-solution treated Mg-4Y-3Nd-1.5Al alloy. The Mg-4Y-3Nd-1.5Al alloy has an obvious aging hardening effect and the mechanical property can be improved obviously by solution + aging treatment. The yield strength, ultimate tensile strength and elongation of Mg-4Y-3Nd-1.5Al alloy after solution (525℃×6h+550℃×12h)+peak aging (225℃×10h) are 85MPa, 262MPa and 6.5%, respectively. The high density and fine precipitation β" and β" are responsible for the excellent mechanical properties of heat treated Mg-4Y-3Nd-1.5Al alloy.