Study On Microstructure Refinement And Properties Of Al-Mg₂Si Alloy

This topic studied the impact on mechanical properties of Al-Mg2Si alloy as well as morphology and distribution of Mg2Si by adding different content compounds, alloy elements, intermediate alloy, and obtained the best element and the element content of which improving the mechanical properties of Al-Mg2Si alloy.The results showed that the volumetric fraction of Mg2Si and the dimension of crystal grains are larger with increase of the Al-Mg2Si alloy and became irregular lumped, with the increases of content of Mg2Si. Adding appropriate amount of compounds, alloy elements, intermediate alloy can significantly refine the grain of Mg2Si, improve their shape and distribution, circle primary Mg2Si to a certain degree, meanwhile, it could also inhibit the anisotropic growth of Mg2Si phase in eutectic phase.When takes up 0.6% CaCO3 of been able to inhibit the dendrite growth of the primary crystal Mg2Si and make the primary Mg2Si phase evenly distributed in the matrix; the content of element P is 0.8%, the phase of Mg2Si showed the distribution of regular multilateral body; when P-Cu alloy is controlled at 0.6%, the microstructure of primary crystal Mg2Si more detailed, meanwhile, the microstructure has became smaller and sharp corners disappeared; when input of element Bi is controlled at 3% the microstructure of primary crystal Mg2Si was the best and the mechanical properties of Al-Mg2Si alloy was the highest. In takes several grain refiner, the shape of Mg2Si is the best with Bi addition better than P-Cu, and the last are P, CaCO3.P element and P-Cu alloy on Al-Mg2Si intermediate alloy Mg2Si primary phase of the mechanism is similar, and are mainly by P metamorphism, the microstructure of the alloy can be improved. The effect of compounds, alloy elements, intermediate alloy on the mechanical properties of Al-Mg2Si alloys was discussed, the performance of tensile strength, percentage elongation, and hardness of the alloy showed a trendency which increase first and then decrease with the increase amount of these elements.The microstructure of AlTiC refiner is different which prepared at different temperatures, and refining effect on Al-Mg2Si alloy is different. The results show that the microstructure of AlTiC refiner prepared by adding potassium titanium fluoride (K2TiF6) and graphite powder to the aluminum melt without any unreacted carbon, only contains TiAl3 phase and TiC phase, refining effect of AlTiC refiner prepared under this conditions is the best.