Microstructure and formation mechanism of titanium matrix composites coating on Ti-6Al-4V by laser cladding

CAI Lifang, ZHANG Yongzhong, and SHI Likai National Engineering Research Center for Nonferrous Metal Composites, General Research Institute for Nonferrous Metals, Beijing 100088, China

摘 要：Laser cladding experiments were done on a 5-kW continuous wave CO2 laser to synthesize TiC and TiB rein- forced titanium matrix composite coatings on Ti-6Al-4V alloy with a mixture of Ti and B4C precursor powder. The ther- modynamics of the reactions were calculated and analyzed. The microstructure and phase evolution of TiB and TiC com- posites were investigated. The results showed that the chemical reaction between Ti and B4C would release much heat, and these compounds, TiC, TiB, and small amount of TiB2, can be formed on the surface of Ti-6Al-4V alloy if the supplied en- ergy is sufficient to excite the reaction among the initial products. A good metallurgical bond between the coating and the substrate can be achieved. The microhardness of coating was irregular and the maximum value was approximately HV600.

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