AlSi7Mg合金半固态压铸件热处理强化机理研究

对AlSi7Mg合金(A356)半固态压铸件和液态压铸件进行了不同工艺的固溶与时效热处理，分析了其显微组织与疏松度，测定了硬度、拉伸强度及延伸率等力学性能。实验得出，铝合金半固态压铸件原始态的力学性能优于液态压铸件，并且半固态压铸件时效强化效果尤其明显，拉伸强度可达330MPa以上，延伸率10％以上。这主要是由于半固态压铸件比液压件具有更加致密，且为球状的非树枝晶组织。铝合金半固态压铸件时效强化，机理主要归于弥散析出Mg2Si强化相。

Study on the Heat Treatment Strengthening of Semi-Solid Die Casting of AlSi7Mg Alloy

Semi solid die castings and liquid die castings AlSi7Mg alloy (A356) were solution treated and aged under different conditions. Then the microstructure, porosity, hardness, tensile strength and elongation of die castings or heat treated parts were measured. The results show that the mechanical properties of semi solid die castings of aluminum alloy are superior to that of the liquid die castings. The ageing strengthening of semi solid die castings is more significant than that of liquid die castings for A356 aluminum alloy. The tensile strength of the aged semi solid die castings is more than 330MPa with the elongation more than 10%. The non dendrite microstructure of semi solid die castings and dendrite microstructure are responsible for the difference of mechanical properties. The ageing strengthening of semi solid die castings is mainly contributed to the dispersive precipitation of phase Mg\-2Si.