Mg-Zn-Al系变形镁合金的显微组织和力学性能

Microstructures and mechanical properties of Mg-Zn-Al wrought magnesium alloys

制备了成分基于Mg-(3-5)Zn-(1-3)Al的5种ZA系镁合金,并研究了合金在铸态和热挤压态的显微组织和力学性能.在ZA系列的铸态镁合金中,将Zn含量(质量分数)固定在3%,提高Al含量,则第2相由致密的共晶相ε(Mg51Zn20)变成呈典型的离异共晶形貌的τ(Mg32(Al,Zn)49)相.在ZA31基础上增加Zn含量没有引起合金显微组织中组成相发生变化,但中间相ε的体积分数增加.在280℃温度下的热挤压过程中,合金发生了动态再结晶,组织显著细化,且铸态组织中出现的中间相大部分溶入α-Mg基体.ZA系合金铸锭热挤压后,合金的强度和塑性均得到大幅度改善,其中合金ZA51具有最好的强度和塑性的匹配.结果表明ZA系合金具有良好的热加工性能.

Five ZA series magnesium alloys based on Mg-（3-5）Zn-（1-3）Al are prepared and their microstructures and mechanical properties under as-cast and extruded conditions are investigated.When the Zn mass fraction is fixed on 3%,as the Al content is increased,the second phases of alloys are transformed from a dense eutectic phase ε（Mg51Zn20） to phase τ（Mg32（Al,Zn）49） which shows divorced eutectic morphology.Increasing Zn content based on ZA31 does not result in any changes of phase constitution but increases the volume fraction of the ε phase.After extrusion at 280℃,most of the inter-phases existing in the as-cast microstructure are dissolved into the matrix and the microstructures of the alloys are significantly refined due to recrystallization occurring during the extrusion.Both the strength and ductility of the alloys prepared are notably improved after the extrusion and the alloy ZA51 exhibits higher mechanical properties than the other alloys.Results show that the ZA alloys have good thermal workability.