Fabrication process of metal matrix composite with nano-size SiC particle produced by vortex method

The fabrication of metal matrix composite (MMC_p) by vortex process is the general method due to the advantage of its convenience. However in the case of fine particles the surface property of the particle appears dominantly, especially in nano-size particles the agglomeration occurs and the fabrication of MMC_p is reduced to be difficult. It is analyzed that the strength of the MMC_p is dominated by the ascent of the dislocation density. Further, as the dispersion strengthening mechanism can be anticipated, dispersions of more fine particles into the matrix are required. In this study, the influences on various primary factors for solving an agglomeration problem are examined using SiC particles of 0.3 μm (the minimum diameter in the market) into 6061 Al alloy by the vortex method. From this study, the following results are obtained. (1) It is found that MMC_p with no agglomeration can be fabricated by conducting the following procedure; pre-treatment, disagglomeration of powder, Ca addition and stirring in the semi-solid range. (2) It is deduced that the main factors of forming the agglomeration in the matrix of MMC_p are the yield of SiO₂ on the surface of SiC and the reduction of the void ratio of SiC powder.