等通道转角挤压对Mg-1Gd、Mg-2Zn二元合金的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

摘要:

本文使用金相、EBSD等手段研究了等通道挤压对Mg-1Gd、Mg-2Zn两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一倍。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，并逐渐演化为大角度晶界。

Abstract:

This article uses metallographic and EBSD techniques to study the effects of equal channel angular pressing on the microstructure and mechanical properties of two binary alloys, Mg-1Gd and Mg-2Zn. The results show that under the same pressing conditions, Mg-2Zn alloy fully recrystallized, resulting in grain growth and coarsening, and the strength and plasticity did not change with the number of pressing passes. Mg-1Gd alloy only partially recrystallized after pressing, with a microstructure consisting of fine dynamic recrystallized grains and deformed grains. With an increase in the number of pressing passes, the degree of recrystallization increased, leading to a doubling of the alloy"s tensile strength and plasticity. This was related to the greater inhibition of recrystallization and grain growth by the solute atom Gd compared to Zn. The recrystallized grains had a dispersed orientation, while the grains that did not recrystallize in Mg-1Gd alloy had a c-axis orientation that deviated 45° from ED to TD, which was consistent with the detection of macroscopic texture. A large number of small-angle grain boundaries formed within the grains, and rotations around the c-axis occurred on both sides of these boundaries, gradually evolving into large-angle boundaries.