重熔时间和模具温度对AZ63H合金组织和性能的影响

Effects of Reheating Time and Mould Temperature on Microstructure and Tensile Properties of Thixoformed AZ63H Magnesium Alloy

研究了部分重熔时间、模具温度对于触变成形AZ63H镁合金微观组织和力学性能的影响。结果表明,抗拉强度和伸长率随着部分重熔时间的延长和模具温度的升高先上升后下降。这是因为,相对于金属型铸造的AZ63H,触变成形大大减少了气孔率,也影响了熔体中溶质的分布,使得β-Mg17Al12相中的Al元素在初生α相中的固溶度也发生了很大的改变,即空隙、杂质、气孔等缺陷减少甚至消失,固溶强化增加,提高了材料的力学性能,在模具温度为300℃时,抗拉强度和伸长率的最大值分别为273MPa和10.3%。

The influences of processing parameters, such as reheating time, mould temperature, on microstructure and tensile properties of thixoformed AZ63H magnesium alloy were investigated. The re- suits indicate that the tensile strength and elongation are increased firstly and then decreased with increasing in the reheating time and the mould temperature. Compared with the permanent mould casting, the thixoforming significantly decrease gas pores and change the solute distribution in the AZ63H melt, thus affect the A1 solubility from β-MglzAll2 phase in primary a-Mg phase, which are responsible for the improvement of tensile strength and elongation as a result of the decease of porosities, inclusion and gas holes as well as the solid solution strengthening. The maximum tensile strength and elongation reach up to 273 MPa and 10.3%, respectively, at 300 ℃.