流变压铸成形镁合金AZ91D的显微组织与性能

采用双螺杆机械搅拌法制备半固态镁合金浆料,对比研究了液态压铸与半固态流变压铸成形镁合金AZ91D的组织与性能,探讨了半固态成形镁合金铸件的热处理强化机制.试验结果表明,流变压铸成形铸件与液态压铸成形铸件在铸态时的力学性能相当;由于半固态成形减轻了铸件内部气孔、偏析等铸造缺陷,因而T4和T6热处理均明显地提高了半固态成形镁合金铸件的力学性能.研究还得出,液态压铸成形镁合金铸件经过固溶处理之后,其抗拉强度和伸长率也有所提高,但是,时效处理明显地恶化了铸件的力学性能.

Microstructure and mechanical properties of magnesium alloy AZ91D produced by rheo-diecasting process

The semi-solid slurry of AZ91D magnesium alloy was prepared by twin-screw stirring mixer,the microstructure and mechanical property of semi-solid formed magnesium alloy AZ91D produced by rheo-diecasting and conventional die casting using the slurry were investigated,respectively.The strengthen mechanism of the semi-solid formed magnesium alloy after heat treatment was analysed by EDS.The results show that the mechanical properties of semi-solid formed magnesium alloy are almost equivalent to die casting magnesium alloy in as-cast state.Owing to decrease of the porosity and less segregation in casting,the mechanical properties of semi-solid formed magnesium alloy are enhanced markedly by T4 and T6 heat treatment.Furthermore,the result indicates that the tensile strength and elongation of magnesium alloy formed by conventional die casting increase after T4 heat treatment,but the mechanical properties are deteriorated distinctly after T6 heat treatment.