Thermal expansion behaviors of ZnAl₂O₄-coated aluminum borate whiskers reinforced aluminum composites

Pure aluminum composites reinforced by ZnAl₂O₄-coated aluminum borate whiskers were fabricated by a squeezing cast technique. Interfacial microstructures of the composites were observed using a transmission electron microscope (TEM). Thermal expansion behaviors of the composites were investigated in the range from 50 to 400°C. Effects of heat-treatment and thermal cycling on the thermal expansion behaviors of the composite were also investigated. The results show that the coefficient of thermal expansion (CTE) of the composites significantly decreases with the coating contents increasing. The average CTE of the composites further decreases after heat-treatment or thermal cycling.