Microstructure evolution of single crystal WCp reinforced Ti-6Al-4V metal matrix composites produced at different cooling rates

Laser melt injection (LMI) and vacuum arc melting (VAM) were explored to prepare single crystal WC particles (WCp) reinforced Ti-6Al-4V metal matrix composites (MMCs). The microstructure evolution of the produced WCp/Ti-6Al-4V MMCs and the interfacial reaction between WCp and liquid Ti at different cooling conditions were investigated. The interfacial reaction of WCp with Ti was sensitive to the cooling rate of the melt pool. The formation of the compact TiC layer during the rapid cooling rate in LMI intercepted the dissolution of WCp and inhibited the interfacial reaction and consequently resulted in the formation of thin reaction layers around WCp. Under the condition of slow cooling rate in VAM, the reaction between WCp and Ti melt was rather intensive and thick reaction layers consisting of W2C and TiC were formed.