Mg-0.5%Zn-0.5%Zr-RE合金的时效强化研究

Aging Strengthening Study of the Mg-0.5%Zn-0.5%Zr-RE Alloy

对挤压制备的Mg-0.5%Zn-0.5%Zr-RE合金进行T5、T6热处理后,进行拉伸力学性能测试。结果表明,T6处理的合金屈服强度稍低于T5,抗拉强度达到313MPa,高于T5处理的289.5MPa。金相显微组织观察表明,合金经T5处理仍保留着挤压状态的组织特征;TEM结果表明,合金在T6时的强化主要与2种过渡相β″和β′脱溶并与位错的相互作用有关,520℃,2h固溶+200℃时效时,Mg-0.5%Zn-0.5%Zr-2.2%Nd-4.0%Y合金的脱溶序列为:SSSS→β″→β′→β。

The Mg-0.5%Zn-0.5%Zr-RE alloy was prepared by extrusion and then T5 and T6 heat-treatments were carried out. The tensile mechanical properties were tested. Results indicate that the yield strength of the alloy in T6 state is a little lower than that in T5 state. The tensile strength of the alloy at T6 state is 313 MPa,higher than 289.5 MPa in T5 state. OM observation indicates that the T5 alloy remains the extruded microstructure. TEM results show that the strengthening of Mg-0.5%Zn-0.5%Zr-2.2%Nd-4.0%Y in T6 state originates from the precipitation of β″ and β′ and the interaction of dislocation. The precipitation order of Mg-0.5%Zn-0.5%Zr-2.2%Nd-4.0%Y alloy is SSSS→β″→β′→β under 520 oC,2 h solution ＋ 200 oC aging.