Abstract: TiAlSi+xB₄C coatings were prepared on the surface of Ti-6Al-4V alloy by laser cladding, and the effects of different B₄C content on microstructure, microhardness and wear resistance of the coatings were analyzed. The results show that different content of B₄C makes little difference in the phase type of the coating. The micro morphology of the clad coating is composed of granular crystals, layered crystals, cell crystals and short rod crystals. The microhardness distribution of the coatings with different content of B₄C is about the same, but is obviously improved compared with the substrate. With the increase of B₄C content, the microhardness tends to increase on the whole, when the content of B₄C is 8%, the microhardness reaches the highest, that is 1216 HV0.1, about 4.2 times of the substrate. However, when the B₄C content is much higher, the hardness decreases and microcracks appear. Wear experiments show that the wear resistance of the coatings with different content of B₄C is significantly better than that of Ti-6Al-4V alloy substrate, and the coating with 8% B₄C has the minimum wear loss. The results show that the cladding of coating with different content of B₄C obviously improves the surface properties of the Ti-6Al-4V alloy substrate.

Key words: laser cladding, Ti-6Al-4V alloy, B₄C, microstructure, microhardness, wear resistance