STRUCTURAL FEATURE OF CAST Al-BASE COMPOSITE

An observation was carried out on the feature of microstructure, fracture and worn surface of the Al-base composite prepared by rheocasting with graphite, SiC and SiO_2. The a solid solution, Si, CuAl_2 and allied eutectics are found to nucleate and to grow up along the surface of particulates added during solidification of the compslurry. The short-range movement of the particulates may distribute more uniformly in matrix owing to rapidly raising temperature of the composlurry before casting. Over the particulate, a transition layer connects with the matrix, and the active element Mg accumulates more or less. Thus, the firm bond is joined between the particulate and matrix, and it makes no more pore and crack on the microstructure of fractured or worn surface.