电磁搅拌辅助流变挤压铸造Mg-6Gd-3Y镁合金的显微组织和力学性能

Microstructure and mechanical properties of rheo-squeeze casting Mg-6Gd-3Y alloy by electromagnetic stirring

通过电磁搅拌制备了Mg-6Gd-3Y(VW63)稀土镁合金半固态浆料,研究了电磁搅拌工艺参数对合金半固态浆料组织的影响,探讨了半固态浆料初生相的形成机理;并对半固态浆料进行了流变挤压铸造成形,研究了压力对流变挤压铸造合金组织和性能的影响。结果表明:电磁搅拌制备VW63合金半固态浆料的最佳工艺参数为浇注温度620℃、搅拌电压350 V、搅拌频率15 Hz,VW63合金半固态浆料的初生相形成机理为枝晶熔断。当压力为120 MPa时,流变挤压铸造合金有着更好的组织与性能,平均晶粒尺寸43.57μm,其屈服强度、抗拉强度和伸长率分别为119 MPa、156 MPa和6.9%,均优于重力铸造和液态挤压铸造合金。

Mg-6Gd-3Y(VW63)alloy semi-solid slurry was prepared by the electromagnetic stirring.The effects of electromagnetic stirring process parameters on the microstructure of VW63 alloy semi-solid slurry were studied,and the formation mechanism of primary phase of semi-solid slurry was discussed.The semi-solid slurry was formed by rheological squeeze casting,and the effects of pressure on the microstructure and properties of rheo-squeeze casting alloy were studied.The results show that the optimal process parameters for the preparation of VW63 alloy semi-solid slurry by the electromagnetic stirring are pouring temperature of 620℃,stirring voltage of 350 V and stirring frequency of 15 Hz.The formation mechanism of primary phase of VW63 alloy semi-solid slurry prepared by electromagnetic stirring is dendrite melting.When the pressure is 120 MPa,the rheo-squeeze casting VW63 alloy has better microstructure and properties,with average grain size of 43.57μm.The yield strength,ultimate tensile strength and elongation are 119 MPa,156 MPa and 6.9%,respectively,which are better than those of the gravity casting and liquid squeeze casting alloys.