Microstructure characteristics of laser alloying composite coatings in nitrogen protective atmosphere

Abstract

This work is based on microstructural characteristics of Ti-B4 C-C laser alloying composite coatings on Ti-6Al-4V alloy in nitrogen protective atmosphere. Test results indicated that laser alloying of Ti-B4 C-C pre-placed powders on titanium alloys substrate can form ceramics reinforced hard alloying coatings, which increased the micro-hardness of the substrate. Test results also indicated that the Ti(CN) phase that was formed in situ in the upper coating was undeveloped dendritic, and thus reduced the possibility of crack formation in alloying coating. Moreover, the TiB and TiC phases were produced in alloying coating, which corresponded to its (210) and (220) crystal planes, respectively.