VALIDATION OF PARTICLE DISTRIBUTION THEORIES ON STIR CAST METAL MATRIX COMPOSITES

Metal matrix composites have been prepared with alpha-Al as the matrix and 7 wt.% of Al2O3 as dispersoids of size range 50-100 mu m. The metallurgical parameters have been experimentally determined and compared with the theoretical concepts reported in the literature. Since these composites include two or more different phases, the primary challenge was to obtain a uniform dispersal of the ceramic particles in the matrix and obtain homogeneity in the microstructure. The distribution of particles in molten slurry depends on many factors such as the density difference of the melt and the particles, pouring temperature, the velocity of solidification front, and the thermal diffusion ratio of particle to the melt. A minimum particle dispersion number is desirable for the uniform distribution of particles. The metallurgical and processing parameters, which govern the retention, distribution, and rejection of the particles in the matrix, are presented in this work.