挤压Mg-12Gd-1Er-xSn-0.5Zr合金的微观组织和力学性能研究

Investigation on microstructure and mechanical properties of as-extruded Mg-12Gd-1Er-xSn-0.5Zr alloys

稀土镁合金因优异的力学性能而备受关注,在航空航天、国防军工、汽车轨道等领域具有广阔的应用前景。添加其他合金化元素,研究其他非稀土合金元素对稀土镁合金的微观组织、时效行为及力学性能的影响规律是目前稀土镁合金研究的热点。本文将少量的Sn(0,0.2,0.4,质量分数,%)元素添加至Mg⁃12Gd⁃1Er⁃0.5Zr(GE121K)合金中,制备了GE121K⁃xSn挤压合金,通过时效硬化处理研究了Sn元素对合金硬化行为的影响规律。结果表明,添加Sn元素导致合金中形成了一种新型的MgSn(Gd,Er)相,它的含量随Sn元素增加而升高。MgSn(Gd,Er)相可显著促进合金中动态再结晶(DRX)的发生,但它含量变多、尺寸粗化也明显恶化了合金的强度和塑性。另外,Sn元素的添加使合金峰值硬化时间提前,但峰值硬度略有降低。

The Mg-RE(RE standing for rare earth)alloys have attracted much attention due to their excellent mechanical properties.The Mg-RE alloys are considered as a candidate for broad application in aerospace,national defense industry and automobiles et al.Adding other alloying elements except RE,the influence of other elements on microstructure,aging behavior and mechanical properties were investigated recently.In this work,a trace addition of Sn(0,0.2,0.4,mass fraction,%)was added into Mg-12Gd-1Er-0.5Zr(GE121K)alloy,and new kinds of as-extruded GE121K-xSn alloys are pro⁃duced.Also,the effects of Sn on the aging hardening response of the GE121K are studied.The results show that the addition of Sn element leads to a formation of a new kind of second phase of MgSn(Gd,Er)in the GE121K alloy,and the volume fraction and size of this second phase increases as the con⁃tent of Sn increases.This second phase plays an important role in stimulating dynamic recrystallization(DRX).However,more content and coarser size of this second phase also deteriorates the strength and plasticity of these alloys.In addition,the addition of Sn elements could advance the time for peak hardness early,but the hardness values are slightly reduced.