Effect of Vac Die Casting on the Microstructure and Properties of AZ91 Magnesium Alloy

In order to improve the quality of die-casting magnesium alloy, the influence of vacuum die-casting process conditions on the structure, mechanical properties and corrosion properties of AZ91 was studied by optical microscope, scanning electron microscope, mechanical property test, weightlessness method and electrochemical test. The results show that vacuum die casting can significantly reduce the porosity of the castings, improve the density and uniformity of the structure, the grains are fine, the average grain size is about 30μm, and the morphology and distribution of the second phase Mg17Al12 phase are uniformly distributed in flakes and networks At the grain boundary. Compared with ordinary die-casting, the tensile strength, yield strength, elongation and hardness of vacuum die-casting AZ91 are increased by 10.19%, 33.07%, 40.63% and 13.04% respectively. The corrosion current density of vacuum die-casting AZ91 decreased by 15.92%, and its 18h corrosion rate in 3.5% NaCl solution dropped to 33.76% of that of ordinary die-casting AZ91 alloy.