Laser Rapid Preparation Ti_<em>x</em>Al_<em>y</em>-TiN Composite Coating

Abstract

The TixAly-TiN composite coatings were in-situ synthesized on Ti-6Al-4V alloy surface by using laser nitriding method. The phase composition, microstructure and microhardness were invesitigated. The results show that the coating is mainly composed of TiN reinforced particles and TixAly intermetal matrix. With increase of the depth from the coating surface, the volume fraction of TiN phase decreased and that of TixAly intermetal matrix increased. Moreover, the size of the TiN phase and the microhardness value of the coating decreased with increase of the depth from the coating surface. The microcracks and pores cannot be found in the coating. The thickness of coating is uniform, and forms a good metallurgical combination between coating and substrate. Along the direction of laser melting depth, the elements of N and Al distribute evenly. The microhardness of coating increases significantly, and gradually reduces from coating to the substrate.

Keywords

• laser gas nitriding
• Ti_<em>x</em>Al_<em>y</em>-TiN
• microhardness
• microstructure