微量Ca、Y元素对AZ91镁合金动态再结晶及力学性能的影响

为同步提升AZ91镁合金强度及延性,研究了微量Ca、Y元素对AZ91镁合金热变形过程中动态再结晶及力学性能的影响。结果表明: Ca、Y元素的引入减少了Al元素在AZ91镁合金中的偏聚,减少了Mg₁₇Al₁₂相的动态析出,从而抑制了低温热变形过程中的动态再结晶,同时细小弥散分布的Al₂Y相在高温时促进了动态再结晶的发生。Ca、Y元素复合添加,引入大量弥散分布的Al₂Y,使完全再结晶后的组织更加细小,提升了力学性能。AZ91+Ca+Y镁合金673 K热压后室温压缩延伸率和强度分别达到了16.5%和392.55 MPa,比AZ91镁合金分别提升了16.2%和8.56%。

Effects of Trace Ca and Y Elements on Dynamic Recrystallization and Mechanical Properties of AZ91 Magnesium Alloy

To improve both the strength and ductility of AZ91 magnesium alloy, effects of Ca and Y elements on the evolution of AZ91 magnesium alloy were studied. The results showed that the introduction of Ca and Y reduced Al clustering in AZ91 magnesium alloy, as well as dynamic precipitation of Mg₁₇Al₁₂ phase, thus inhibited dynamic recrystallization during thermal deformation at low temperatures, while the small dispersed Al₂Y phase promoted the occurrence of dynamic recrystallization at high temperatures. A mixed addition of Ca and Y introduced a large number of dispersed Al₂Y, which made the grains after complete recrystallization even smaller and thus strengthened the mechanical properties. The elongation and strength of AZ91+Ca+Y magnesium alloy after thermal compression under 623 K were 16.5% and 392.55 MPa, respectively, indicating 16.2% and 8.56% higher than those of AZ91 magnesium alloy.