Zn对Mg-Gd-Y-Zr镁合金微观组织和力学性能的影响

Effect of Zn-addition on the Microstructure and Mechanical Properties of Mg-Gd-Y-Zr Alloy

Zn元素的添加对Mg-Gd-Y-Zr合金的微观组织和力学性能具有重要影响,特别是LPSO结构的演变对高性能镁合金的产业化应用具有重要的作用。为研究Zn对Mg-Gd-Y-Zr合金微观组织演变和性能影响,对不同Zn元素含量的Mg-10Gd-4Y-0.5Zr-xZn(x=0,1,2,质量分数,%)铸棒进行挤压处理,采用OM、SEM、XRD、和TEM对挤压试样进行了组织观测,并对试样的力学性能进行检测。结果显示,挤压状态Mg-10Gd-4Y-0Zn-0.5Zr由基体α-Mg和少量的Mg-RE微粒相组成。随着元素Zn的添加,试样的相组成变为大量基体α-Mg、晶界流线形LPSO结构、晶粒内部微小层片状LPSO及少量随机分布Mg-RE微粒相。随着元素Zn的不断增加,晶粒尺寸不断细化,细晶强化效果不断增强,使得试样的强度显著提升,而试样伸长率呈现先增强后减弱的趋势。

The addition of Zn has a significant impact on the microstructure and mechanical properties of Mg-Gd-Y-Zr alloy.In particular,the evolution of the LPSO structure plays an important role in the application of high-performance magnesium alloys.To investigate the effect of Zn on the microstructure evolution and properties of the Mg-Gd-Y-Zr alloy,Mg-10Gd-4Y-0.5Zr-xZn(x=0,1,2,mass fraction,%)alloys with different Zn contents were prepared by extrusion.The microstructure of the as-extruded alloys was observed by OM,SEM,XRD and TEM,and the tensile properties at room temperature were tested.The results show that the as-extruded alloy without Zn consists of theα-Mg matrix and a small amount of the Mg-RE phase.With the addition of Zn,the alloy consists ofα-Mg with lamellar 14H-LPSO in the matrix,linear flow 14H-LPSO at the grain boundary and the Mg-RE phase.The grain size of the as-extruded alloy continuously decreases and the effect of fine grain strengthening increases with increasing Zr content.As a result,the strength of the alloy increases,while the elongation of alloys increases primarily and then weakens with the addition of Zr.