Abstract

The effects of Zr addition (0, 0.5 and 1 wt%) and extrusion ratio (6:1 and 12:1) on microstructure and mechanical properties of the Mg–5Sn alloy were studied. Results showed that the dendritic structure of the as-cast M–5Sn alloy gradually transformed into a nearly globular structure with Zr addition. The effect of Zr addition was evident through refining the microstructure, promoting the tendency to form partially divorced eutectic and increasing the Mg₂Sn volume fraction, which improved the thermal stability of the alloy during homogenizing treatment at high temperatures. Hot extrusion was found to be very effective for enhancing both strength and ductility of the Mg–5Sn–xZr alloys. Grain refinement induced by twin dynamic recrystallization and dynamic precipitation of fine particles were realized as the main strengthening mechanisms of the extruded alloys. It was found that an increase of the extrusion ratio led to relatively coarser grains, lower yield strength, and higher hardening capacities. However, the Mg–5Sn–1Zr alloy extruded with the area-reduction ratio of 12 exhibited the best combination of tensile strength and elongation of 243 MPa and 10.6%, respectively. Moreover, tensile fracture studies revealed the intergranular cracking and quasi-cleavage fracture as the dominant fracture modes of the as-cast and extruded alloys, respectively.

Graphic Abstract

中文翻译：

---

热挤压对Mg-5Sn-xZr合金组织和力学性能的影响

摘要

研究了Zr添加量（0、0.5和1 wt％）和挤压比（6：1和12：1）对Mg-5Sn合金的组织和力学性能的影响。结果表明，铸态M-5Sn合金的树枝状结构在添加Zr后逐渐转变为近球形。添加Zr的效果通过细化微观结构，促进形成部分离婚的共晶趋势和增加Mg _{2来体现。}Sn体积分数，提高了高温均质化处理期间合金的热稳定性。发现热挤压对于增强Mg-5Sn-xZr合金的强度和延展性非常有效。实现了双动态再结晶和细颗粒的动态沉淀引起的晶粒细化，这是挤压合金的主要强化机理。已经发现，挤出比的增加导致相对粗大的晶粒，较低的屈服强度和较高的硬化能力。但是，Mg-5Sn-1Zr合金以减小的面积比12挤压时，其抗张强度和伸长率分别为243 MPa和10.6％的最佳组合。此外，

图形摘要