The wear behavior of SiC particle-reinforced aluminum alloy matrix composites as journal bearing materials in conformal contact against case hardened AISI 1016 steel under mixed lubrication conditions using SAE 10W30 oil was investigated. The bearings exhibited weight gain, followed by weight loss and subsequent weight gain as the sliding distance increased. Iron transfer and tribo-chemical reaction product formation were responsible for the observed weight gain. The surfaces of the composites contained transferred iron, layers rich in Fe, S, P and Zn, and hard tribo-deposits of high phosphorus concentration. The hard tribo-deposits were thought to be an important factor in lubrication breakdown and contact failure.Presented as a Society of Tribologists and Lubrication Engineers paper at the STLE/ASME Tribology Conference in New Orleans, Louisiana, October 24-27, 1993