退火工艺对Zn/AZ31/Zn复合板材界面微观结构及力学性能的影响

采用热轧工艺制备Zn/AZ31/Zn复合板材,研究退火温度与时间对板材界面微观组织及力学性能的影响。结果表明:退火温度对界面扩散层的形成影响较大,低温退火无法形成良好的界面扩散层,而在200℃退火,可获得由Mg4Zn7和MgZn2相组成的良好的冶金结合界面。较高的温度(300℃)导致界面脆性Mg2Zn11相的析出,而引发微裂纹。在同一温度下,退火时间的延长仅影响扩散层的厚度,对其相组成没有影响。退火处理使板材的强度降低,但是塑性有所提高,在200℃热处理1 h获得的复合板材综合力学性能较好。

Effect of annealing process on interfacial microstructure and mechanical properties of Zn/AZ31/Zn clad sheets

Zn/AZ31/Zn clad sheets were prepared by hot rolling process.The effects of annealing temperature and time on the interface microstructure and mechanical properties of the clad sheets were investigated.The results show that the annealing temperature has great influence on the formation of interfacial diffusion layer.The interfacial diffusion layer cannot be formed at low annealing temperature,but good metallurgical bonding interface can be obtained,which is composed of Mg4Zn7 and MgZn2 phases annealed at 200℃.The higher annealing temperature(300℃)leads to the precipitation of the brittle Mg2Zn11 phase at the interface,thereby inducing microcracks along the interface.At the same annealing temperature,the extension of time only affects the thickness of the diffusion layer,and has no effect on its phase formation.The strength of the sheets is reduced after annealing,but the plasticity is improved.The clad sheets obtain better mechanical properties when annealed at 200℃for 1 h.