| The precipitation behavior of SiC whisker reinforced 2124 aluminum metal matrix composites was investigated, especially the influence of existing oxides on strengthening was emphasized. Two kinds of composites, one made by powder metallurgical process and the other by squeeze casting one, were used to study the differences in precipitation behavior. The specimens were heat-treated with an appropriate conditions, and microstructural changes were observed by using electron microscopy, DSC and micro hardness test. In the case of PM specimens, the influence of precipitates and hardness were increased by the amount of oxides formed on aluminum powder surface. TEM study shows that the oxides serve as an anchoring point for the mobile dislocation and diffusion path of precipitate formation. Therefore, it is suggested that the presence of oxides formed on aluminum powders, strongly affect the amount of precipitate in Al-SiCw composite. |
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