等通道转角挤压对Mg-1Gd、Mg-2Zn二元合金组织及力学性能的影响

Effect of Equal-Channel Angular Extrusion on Microstructure and Mechanical Properties of Mg-1Gd and Mg-2Zn Alloys

使用OM、EBSD等手段研究了等通道转角挤压(ECAE)对Mg-1Gd、Mg-2Zn2种二元合金组织和力学性能的影响。结果表明,在相同挤压条件下,Mg-2Zn合金发生完全再结晶,晶粒长大粗化,且强度塑性不随着挤压道次变化;Mg-1Gd合金则只发生了部分动态再结晶,组织为细小的动态再结晶晶粒和变形晶粒,伴随挤压道次的增加,再结晶程度提升,合金的抗拉强度与塑性增加了1倍。这与溶质原子Gd比Zn更能抑制再结晶和晶粒长大有关。Mg-1Gd合金的再结晶晶粒的取向分散,而未再结晶的晶粒c轴取向由ED向TD偏转45°,这与宏观织构的检测相互印证,晶粒内部产生大量的小角度晶界,小角度晶界两侧发生围绕c轴的转动。

The effects of equal-channel angular extrusion on the microstructure and mechanical properties of two binary alloys,Mg-1Gd and Mg-2Zn were studied by OM and EBSD.The results show that under the same extrusion conditions,Mg-2Zn alloy fully recrystallizes,resulting in grain growth and coarsening,and the strength and plasticity do not change with the number of extrusion passes.Mg-1Gd alloy only partially recrystallizes after extrusion,with a microstructure consisting of fine dynamic recrystallized grains and deformed grains.With the increase in the number of extrusion passes,the degree of recrystallization increases,leading to a doubling of the tensile strength and plasticity of Mg-1Gd alloy.This is related to the greater inhibition of recrystallization and grain growth by the solute atom Gd compared to Zn.The recrystallized grains have a dispersed orientation,while the grains that do not recrystallize in Mg-1Gd alloy have a c-axis orientation that deviates 45°from ED to TD,which is consistent with the detection of macroscopic texture.A large number of small-angle grain boundaries form within the grains,and rotations around the c-axis occur on both sides of these boundaries,gradually evolving into large-angle boundaries.