等径角挤压制备AZ91D镁合金的组织与性能

研究了铸态AZ91D镁合金在等径角挤压（Equal Channel Angular Extrusion,ECAE）后的室温力学性能和微观组织特征。在力学性能方面,铸态AZ91D镁合金经过1道次ECAE变形后,室温力学性能（屈服强度、抗拉强度、延伸率、弹性模量）由86.3 MPa,146.3 MPa,1.84%,42.5 GPa分别提高到144.1MPa,222.8 MPa,3.49%,47.7 GPa;2道次后变为109.1 MPa,268.3 MPa,4.48%,48.9 GPa。在微观组织方面,挤压1道次后,由于枝状晶粒在等径道弯角处滑动和转动时发生破碎,AZ91D镁合金的晶粒和黑色共晶相Mg17Al12沿挤压方向拉长为条带状;挤压2道次后,黑色共晶相开始部分回溶,共晶相有所减少且呈非连续分布。

Microstructure and Mechanical Properties Evolution of Cast Magnesium Alloy AZ91D after Equal Channel Angular Extrusion

This paper demonstrates the effect of equal channel angular extrusion（ECAE） process on the microstructure and mechanical properties of cast magnesium alloy AZ91D.In terms of mechanical properties,the yield strength,ultimate strength,elongation rate,and elastic modula of AZ91D were increased from 86.3 MPa,146.3 MPa,1.84%,and 42.5 GPa to 144.1 MPa,222.8 MPa,15.15%,and 47.7 GPa after one ECAE pass,and to 109.1 MPa,268.3 MPa,25.48%,and 48.9 GPa after two ECAE passes at room temperature.In terms of microstructure,the dendritic crystal had been crushed because of sliding and rotation motion after the first pass of ECAE process,the crystal and black eutectic phase（Mg17Al12） of AZ91D has been elongated along the direction of extrusion.When the second pass was applied,the black eutectic phase began to remelt,and was reduced and distributed discontinuously.