ZM81-xSn (x = 0, 2, 4, 6, 8 and 10)变形镁合金的组织演变和力学性能

通过对不同Sn含量的ZM81合金的微观组织和力学性能的测得，研究了Sn在ZM81合金中的存在形式和作用机制及不同添加量对合金显微组织和力学性能的影响。研究结果表明：Sn元素主要以Mg2Sn共晶相形式存在，能够细化铸态组织；热挤压过程中，Sn添加能够起到抑制动态再结晶和晶粒细化的作用；T6处理，尤其是双级时效，能显著提升挤压态合金的力学性能，其中ZM81-4Sn合金具有最佳的综合力学性能，抗拉强度、屈服强度和延伸率分别为416MPa、393MPa和4.1%。实验合金高强度主要源于MgZn2和Mg2Sn析出相的双重时效强化效果；相比单级时效，双级时效态合金的析出相细小弥散，因此其力学性能更优。

Microstructure evolution and mechanical properties of ZM81-xSn (x = 0, 2, 4, 6, 8 and 10) wrought magnesium alloys

The microstructure and mechanical properties of the ZM81 alloys with varying Sn contents subjected to the extrusion and T6 treatments were investigated by OM, XRD, SEM, TEM, hardness test and uniaxial tensile test at room temperature, respectively. The results show that after the addition of Sn element, an Mg2Sn eutectic phase is formed, which can refine the as-cast microstructure. Sn element has an obvious effect on refining the microstructure of as-extruded alloys by restricting the occurrence of dynamic recrystallization and restraining the grain growth during extrusion, and improves the mechanical properties. T6 treatments, especially double aging, can significantly increase the strengths of the extruded alloys. Among them, the ZM81-4Sn alloy with double aging exhibits an ultimate tensile strength of 416MPa, a 0.2% yield strength of 393MPa and an elongation of 4.1%. The microstructure characterization suggests that the high strengths of the peak-aged alloys are attributed to the combined precipitation strengthening of the fine and dispersed MgZn2 and Mg2Sn precipitates, and the pre-cipitates after double peak aging are finer than those after single peak aging.