Microstructure and Properties of Ti-Al Based Composite Coating Prepared by Electrospark Deposition Process

Abstract

Ti-Al based composite coating was fabricated on LY12 aluminum alloy surface by electrospark deposition (ESD) process, with γ-TiAl as electrode. The microstructural characteristics, element distribution, microhardness and wear resistance of the coating were investigated. The results show that the coating forms metallurgical bonding to the substrate, which consists of strengthened layer, transition layer and heat affected zone. Besides the Al phase, the coating is also composed of Ti-Al intermetallic compounds and a small mount of Ti/Al oxides and nitrides. The microhardness of composite coating decreases gradually along the depth direction. The sliding wear test results suggest that the worn volume loss of the coating is less than one third of that of the substrate. The abradability of LY12 aluminum alloy is significantly improved. The phases with higher hardness dispersed in the coating increase not only composite coating hardness but also the resistance to micro-cutting and plowing during the sliding wear test. In addition, the excellent sliding wear resistance of composite coating is also related to the metallurgical bonding between the coating and the substrate.