Influence of Semi-Solid Injection Molding on the Microstructure and Properties of AZ91D Mg Alloy
摘要
The effects of semi-solid molding technology on the microstructure and mechanical properties of magnesium alloys were studied. Magnesium alloy samples were fabricated via semi-solid injection molding, and after heat treatment, the microstructure and mechanical properties of the alloys were characterized by microscopic observation and tensile testing. And the stretching test experiment was carried out with a 3 mm plate sample. Mg alloys during semi-solid injection molding are characterized by homogeneous microstructure with fine grain size and improved mechanical properties. Good quality thixoformed components are obtained, showing fine structures with mean grain sizes of 20 ~ 30 μm. Heat treatment of AZ91D Mg alloy greatly affects the amount and the distribution of the secondary phase at the grain boundaries. The hardness varies from 63.47HV to 74.05HV. The tensile strength increases from 125.56 MPa to 150.91 MPa, and its tensile strength increases by 16.8%. And magnesium alloy has good dynamic tensile properties in 0.01 ~ 1 s−1. In comparison with die-casting magnesium alloys, semi-solid injection-molded magnesium alloys, when combined with subsequent heat treatment, exert a synergistic effect on optimizing the microstructure and thus improving the resultant material properties. This finding provides important guidance for the industrial selection of lightweight alloys and the design of their heat treatment processes.