Enhancing the oxidation resistance of TZM alloy by laser-clading MoSi2-TiVAlZrNb composite coating

The MoSi2 coating is an ideal coating system for molybdenum alloys due to the formation of a SiO2 glass phase and its good oxidation resistance in high -temperature service environments. However, the difference in the thermal expansion coefficient between MoSi2 and molybdenum alloy results in cracks in the MoSi2 coating, which has an important effect on the oxidation resistance at high temperature. In this paper, MoSi2 coatings were optimized by the addition of a multicomponent TiVAlZrNb on a TZM alloy prepared by laser cladding. The results showed that the MoSi2-TiVAlZrNb composite coating had a more uniform structure and fewer internal cracks than the single MoSi2 coating. The mass loss of the MoSi2-TiVAlZrNb composite coating was 0.1500-0.8721 g, which was lower than that of the single MoSi2 coating (0.3885-1.14190 g) at 1000 degrees C-1400 degrees C for the 1 h oxidation test. The higher oxidation resistance of the MoSi2-TiVAlZrNb composite coating was attributed to the dense oxide film formed by the increase in Ti and Al content on the surface and the decrease in the number of cracks, thus reducing the diffusion of oxygen along the cracks to the matrix. Therefore, the addition of TiVAlZrNb multicomponent alloys could provide a new method for the further development of molybdenum alloys in the field of high -temperature oxidation environments.