Growth morphology and solidification behavior of in-situ synthesized TiN and TiB

Abstract

Titanium-based composite coating reinforced by in situ synthesized TiN and TiB particles was successfully fabricated on Ti-3Al-2V alloy by laser cladding with Ti/c-BN powder mixture. The microstructures of in situ synthesized TiB and TiN were compared with needle platelet and dendrite. TiB tends to nucleate and grow on the surface of TiN and grain boundary. In the rapid solidification process, phases crystallization follow the five steps: primary TiN → peritectic structure TiN+α-Ti → primary TiB; → binary eutectic β-Ti+TiB → solid transformation from β-Ti to α-Ti.