FABRICATION, MICROSTRUCTURE, AND WEAR OF Al-10.6Si LASER SURFACE ALLOYED WITH ADDITIONAL SILICON

Abstract A cast Al-10.6 Si alloy has been laser surface alloyed with 9.4, 15, 19, and 35% Si, the coatings have been characterised, and the dry sliding wear against a cast iron surface has been investigated. Except for a few pores, the coatings were relatively uniform in composition, microstructure, and thickness, and had high integrity and continuity with the substrate. The microstructure was very fine, the eutectic composition being displaced to approximately 17% Si. The wear rates of the base alloy, the laser surface melted base alloy, and the laser surface alloyed coatings were similar. The microstructures of the worn pins and the worn cast iron rings are described and discussed. The mechanism of wear is by adhesion, extensive plastic flow, and fracture.