Laser Surface Alloying of (Pre-placed) SiC and Ni-SiC Coating on Commercially Pure Titanium

Results of laser alloying of 100% SiC and 50% Ni + 50% SiC on commercially pure titanium were presented in this investigation. The high hardness Hv800-1200 obtained at 100% SiC and 50% Ni + 50% SiC alloying conditions were due to the presence of various intermetallic phases such as TiC, TiSi, Ti₅Si₃ and NiTi₂. These intermetallic phases present in the laser alloyed surface were validated by EDXRD analysis and the diffusion of Ni, Si, C in titanium responsible for these phase formations was identified by SIMS study. The alloyed layer microstructure consists of dendrites and its density level depends on laser processing conditions. At low level power density the alloyed layer depth was about 0.5 mm with a constant hardness level, whereas at higher level powerdensity the depth of alloyed layer touched a maximum of 1.6 mm with large fluctuation in hardness.