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研究了在Mg-4Al-2Si-0.75Sb合金中加入微量Sb及往复挤压对其组织与性能的影响,重点探讨了基体组织和Mg2Si相颗粒的细化机制,分析了Mg2Si颗粒对再结晶的影响规律。结果表明:加入0.75wt%Sb后的Mg-4Al-2Si-0.75Sb合金中形成Mg3Sb2相,能有效细化粗大的α(Mg)基体组织和汉字状共晶Mg2Si相颗粒,并抑制粗大的块状初生Mg2Si相颗粒的形成;Mg-4Al-2Si-0.75Sb合金在往复挤压过程中发生受位错攀移控制的动态再结晶,通过晶界迁移、亚晶合并与转动机制形成了更为细小的α(Mg)再结晶等轴晶;随着挤压道次的增加,动态再结晶速度加快,晶粒尺寸迅速减小;挤压8道次后,α(Mg)基体和汉字状Mg2Si颗粒尺寸分别由铸态时的30μm和10μm减小到1μm和0.8μm,形成了细小、均匀的α(Mg)等轴晶组织;挤压过程中,汉字状Mg2Si依弯曲机制而破碎成块状或条状,条状Mg2Si依短纤维加载机制而破碎成块状,块状Mg2Si依剪切机制发生破碎,并随挤压道次的增加而呈细小、弥散分布;合金的力学性能随往复挤压道次的增加而显著提高。
The effects of adding trace amounts of Sb and reciprocating extrusion on the microstructure and properties of Mg-4Al-2Si-0.75Sb alloy were investigated. The mechanism of refinement of matrix microstructure and Mg2Si phase grains was discussed. The effect of Mg2Si particles on recrystallization Affect the law. The results show that the formation of Mg3Sb2 phase in Mg-4Al-2Si-0.75Sb alloy with addition of 0.75wt% Sb can effectively refine the coarse α (Mg) matrix and the Chinese character eutectic Mg2Si phase particles and inhibit the formation of coarse Mg-4Al-2Si-0.75Sb alloy undergoes the dynamic recrystallization controlled by dislocation climbing during the process of reciprocating extrusion. Through the grain boundary migration, the subgrain combination and the rotation mechanism form more With the increase of the extrusion pass, the dynamic recrystallization rate increases rapidly and the grain size decreases rapidly. After 8 passes, the α (Mg) matrix and the Chinese character-like Mg2Si The grain size decreases from 30μm and 10μm to 1μm and 0.8μm, respectively, resulting in a fine and uniform α (Mg) equiaxed microstructure. In the extrusion process, the Chinese character Mg2Si is broken into lumps according to the bending mechanism Or strip, strip Mg2Si according to the short fiber loading mechanism and broken into lumps, massive Mg2Si broken mechanism according to the shearing mechanism, and with the increase of the extrusion pass was small, dispersed; mechanical properties of the reciprocating extrusion The increase in pressure increases significantly.