中文摘要：

对AZ91D镁合金消失模铸件进行了近半固态等温热处理,通过光学显微镜、扫描电镜以及金属拉伸试验对其组织和力学性能进行了研究。结果表明,AZ91D镁合金消失模铸件经过530℃×60 min近半固态等温热处理后,合金显微组织中β-Mg17A l12相基本熔入基体,枝晶状的铸态组织在等温处理过程中变得均匀圆整,由此产生的固溶强化作用使材料的力学性能大大提高,抗拉强度达到213.17 MPa,屈服强度达到115.63 MPa,伸长率达到4.11%,等温热处理后的断口呈现明显的韧性断裂特征。

英文摘要：

The microstructures and mechanical properties of AZ91D magnesium alloy by lost foam casting （LFC） were investigated by OM,SEM and tensile test after closing semi-solid isothermal heat treatment. The results show that when the AZ91D magnesium alloy parts are treated by closing semi-solid isothermal heat treatment at 530 ℃ for holding 60 min,the β-Mg17 Al12-phase basically solutionizes in matrix and dendrites as-cast gradually evolves into fine spheroid shape during the holding. The mechanical properties of the alloy are significantly improved after the heat treatment. The tensile strength, yield strength and elongation achieve 213.17 MPa, 115. 63 MPa, and 4. 11%, respectively. The tensile fractographs after the treatment present the obvious gliding fracture characteristics.