Surface properties of the in situ formed ceramic-reinforced composite coating on TA15 alloy

Abstract A hard composite coating was fabricated by laser alloying of the Co-Fe-Al+B ₄ C-Si ₃ N ₄ mixed powders on TA15 (Ti-6Al-2Zr-1Mo-1V) titanium alloy in an open system. The composite coating mainly consisted of γ-Co, TiB ₂ , TiB, TiC _0.3 N _0.7 , SiC, Ti ₃ Al, FeAl, and Co-Ti intermetallics. The TEM diffraction pattern results indicated that the orientation relationship between TiB ₂ and TiC _0.3 N _0.7 was (1 ^- 20)TiB ₂ //(2 ^- 20)TiC _0.3 N _0.7 in such a coating. Furthermore, during the alloying process, a number of Mo and Zr entered into the molten pool from the substrate due to the dilution effect, which refined the microstructures of the composite coating and also increased the amorphous phase content.