Summary: | In this paper, the effect of heat treatment (solution treatment and artificial aging) on the microstructure and properties of as-cast Al5Si1Cu0.5Mg aluminum alloy and its composite reinforced with 1.5 wt.% SiC particles was studied. The results showed that at 520 °C the optimal solution time for the aluminum alloy and its composite is 9 h and 6 h, respectively. After solution treatment, the microstructure of these two materials consists of a uniform distribution of nearly spherical eutectic Si and skeletal γ phase, furthermore, the composite eutectic Si phase is smaller and γ phase is more dispersed. After artificial aging at 175 °C for 6 h, the microstructure of the composite is more dispersed and finer than that of the aluminum alloy on the whole and Al<sub>2</sub>Cu is precipitated. After heat treatment, the microhardness, ultimate tensile strength, and elongation of the aluminum alloy and its composite are higher than those of the as-casts. At the same time, the morphology of tensile fracture surface changes very much from a large area of cleavage plane to a large number of dimples and the tearing ridges become thicker for both the aluminum alloy and its composite.
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