挤压态和时效态Mg-Zn-Mn-Sn-Y合金的组织性能

利用光学显微镜、X射线衍射和扫描电镜等对挤压态和时效态Mg-6Zn-1Mn-4Sn和Mg-6Zn-1Mn-4Sn-0.5Y镁合金的微观组织和力学性能进行研究。结果表明：与ZMT614镁合金相比,添加Y元素后,ZMT614-0.5Y晶粒得到细化,综合力学性能得到提高。Mg-6Zn-1Mn-4Sn-0.5Y合金的相组成为α-Mg、Mg Zn2、Mn、Mg2Sn和MgS n Y相。经过T6热处理后,合金的抗拉强度和屈服强度明显得到提高,伸长率明显被降低。理论计算表明,在挤压态合金中,细晶强化和固溶强化产生重要的作用,而在T6热处理态合金中,析出强化产生决定作用。

Microstructures and mechanical properties of extruded and aged Mg-Zn-Mn-Sn-Y alloys

The microstructures and mechanical properties of Mg-6Zn-1Mn-4Sn and Mg-6Zn-1Mn-4Sn-0.5Y alloys under extrusion and T6 aging conditions were investigated by optical microscopy（OM）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and tensile test. The results show that Y element refines the grains and improves the comprehensive mechanical properties of ZMT614-0.5Y both in as-extruded and T6 states. The phase compositions of Mg-6Zn-1Mn-4Sn-0.5Y are α-Mg, Mg Zn2, Mn, Mg2 Sn and Mg Sn Y phases. After T6 treatment, the ultimate tensile strength（UTS） and yield strength（YS） increase while the elongation decreases severely. For both of these alloys, the theoretical results combined with the experimental values demonstrate that the grain boundary strengthening and solid solution strengthening play an important role in enhancing the YS in the as-extruded state, while the precipitation strengthening is the key factor for the enhancement of YS in the T6 state.