| Based on the background of composite materials in the application of parts, this paper chooses the non-heat Enhanced Al-Mg alloy as the body alloy and fabricates SiC/Al composite materials and then does with heat treatment, hoping to get dimensional stable performance SiC/Al composites without water quenching.This article firstly selected 5A06Al and 5A12Al as the base alloys fabricating SiC/Al composites, at the interface we found Al8Mg5 and Mg2Si phase. The micro-deformation of SiC/5A06Al and SiC/5A12Al stress were separately 167.8MPa and 190.0MPa, residual deformation values of thermal cycling were separately 1.79×10-6 and 1.92×10-6.Taking into account the dimension stability performance, we select 5A06Al as body alloy for system study.The homogenizing behaviour with different cooling rates of SiC/5A06Al composite was investigated. While there were small grains in the matrix with rapid cooling rate, the matrix grain having grown with the slow cooling rate, only polygon dislocation in the matrix. At fast and slow cooling rates, the residual deformation values of thermal cycling were 2.51×10-6 and 2.88×10-6, micro-deformation stress are both 140MPa.The cast composites were annealed with different heat preservation time, there is a lot of material dislocation tangle at 0.5 hours. the base body appeared small grains at 4 hours; At 0.5 hours, the micro-plastic deformation stress and residual value of the thermal cycling were 167MPa and 1.75×10-6, while at 4 hours, the micro-composite material deformation stress and the residual value of thermal cycling were 190MPa and 3.25×10-6.We have studied effects of annealing parameters on composite dimensional stable performance which have been homogenizied. With the decrease of annealing temperature, micro-deformation stress gradually increased, the residual strain value of thermal cycling also decreased as the annealing temperature decreased.When the annealing temperature reduced to 160℃, micro-plastic deformation stress was 190MPa, and the residual strain value of thermal cycling was 3.16×10-6. We compared the effect of holding time on the dimension stability. The residual deformation values of thermal cycling were separately 3.16×10-6 and 3.82×10-6 at 4 hours and 24 hours, micro-deformation stress remained the same.We have studied effects of thermal and colding cycling on composite dimensionally stable performance which have been homogenizied. After thermal and colding cycling, second phase had dispersed in the composite, this phase can effectively pin dislocations slippage and increase micro-deformation stress significantly; but after thermal and colding cycling the residual deformation value of thermal cycling increased.According to all the test in this paper, comparing all the heat treatment process, the best heat treatment process is 330℃holinging for 0.5 hours, the composite micro-plastic deformation stress is 167.8MPa, the residual deformation values of thermal cycling is 1.75×10-6.
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