二次挤压对MB26镁合金棒材组织及性能的影响

采用二次挤压工艺制备MB26(Mg-6.3Zn-0.7Zr-0.9Y-0.3Nd)镁合金棒材,研究不同挤压比对MB26合金组织性能的影响,通过金相(OM)、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等手段分析稀土元素在合金中的分布及其对微观组织的影响。结果表明:合金在二次挤压过程中发生动态再结晶,随着挤压比的增加,再结晶晶粒细化,当挤压比λ=25时,平均晶粒尺寸为1.9μm,合金力学性能达到最优;合金经挤压变形后出现大量W(Mg3Y2Zn3)相和β′(MgZn)相,均呈弥散分布,钉扎晶界,阻碍了动态再结晶晶粒的长大。通过数据拟合得到该合金屈服强度与晶粒尺寸的Hall-Petch关系。

Effect of double extrusion on microstructure and properties of MB26 magnesium alloy rod

MB26 magnesium alloy(Mg-6.3Zn-0.7Zr-0.9Y-0.3Nd) rod was prepared by double extrusion.The effects of extrusion ratio and rare earth elements(RE) on the microstructure and properties of MB26 alloy,as well as the distribution of RE in the alloy,were investigated by OM,XRD,SEM and TEM.The results show that,the dynamic recrystallization occurs during the double extrusion,the recrystallized grain size decreases with the increase of extrusion ratio.When extrusion ratio λ=25,the grain size is 1.9 μm with better mechanical properties.The large amount of dispersed Mg3Y2Zn3(W) and MgZn(β′) phases appear after extrusion pinned the grain boundary and hindered the growth of recrystallized grain.By data fitting analysis,the Hall-Petch relationship of yield strength and grain size was calculated.