微合金化对AZ31组织和力学性能的影响

Effects of Microalloying on Microstructure and Mechanical Properties of Magnesium Alloy

研究了Ca和Zr元素对AZ31镁合金铸态显微组织和力学性能的影响,并探讨其化学成分与组织结构和力学性能之间的变化。结果表明,在AZ31镁合金中加入Ca后,合金的组织明显细化,晶间析出相增多,β-Mg17Al12相数量减少,当Ca含量为0.37%时,在晶界上出现了新相Al2Ca相,Al2Ca相对合金有强化作用,合金的抗拉强度为190.4MPa。当Ca含量达到1.54%时,晶粒尺寸最小为63.4μm;采用电磁-悬浮铸造技术,在AZ31镁合金中加入Zr,可以细化合金的显微组织,提高其力学性能,当Zr含量达到0.07%时,合金的抗拉强度为210.8MPa,与铸态AZ31镁合金相比提高了19.56%,伸长率为12.9%,提高了20.56%。

Effects of Ca and Zr addition on as-cast microstructure and mechanical properties of AZ31 magnesium alloy were investigated. The results indicate that the microstructure of AZ31 magnesium alloy can be refined with Ca addition, in which the precipitates at inter-crystal are increased and β-Mg17Al12 phases are decreased. In addition, the Al2Ca phase is created at grain boundary with 0.37% Ca addition, which can improve the tensile strength of alloy to maximum value of 190.3 MPa as a result of enhancing alloy. The minimum size of 63.4 μm can be obtained in the AZ31 alloy with 1.5% Ca addition. Zr addition can refine the microstructure and improve the mechanical properties of AZ31 magnesium alloy in electromagnetic-suspending casting. Compared with those of as-cast AZ31 magnesium alloy, the tensile strength and elongation of the alloy with 0.07% Zr addition are 210.75 MPa and 12.9%, respectively, increased by 19.56% and by 20.56%, respectively.