A Novel Ti-6Al-4V-xSi Coating with Superior Wear and Oxidation Behavior

Via adding a certain amount of Si on the surface of the Ti-6Al-4V alloy, a novel Ti-6Al-4V-xSi coating is prepared by powder metallurgy method. The results show that an 80 mu m thick transition layer is formed between the Ti-6Al-4V-xSi coating and the matrix, and the addition of Si reduces the thickness of alpha lamellae. Numerous nanosized Ti5Si3 particles can be detected on the interface of the alpha/beta phase, with a size of about 100 nm and approximately spherical. The main wear mechanisms are adhesive wear and abrasive wear, the average friction coefficients, and mass loss of the sample, as well as the width, depth, and area of wear tracks, decrease with the addition of Si. This is because the dispersed Ti5Si3 particles can effectively improve the plastic deformation resistance, cutting resistance, adhesion resistance, and crack propagation resistance of the Ti-6Al-4V-xSi coating. The thermal expansion coefficient of Ti5Si3 is close to that of rutile-TiO2 and Al2O3, which reduces the internal stress between the oxide film and the Ti-6Al-4V-xSi coating, and ultimately reduces the cracking tendency of the oxide film. Therefore, the preparation of Ti-6Al-4V-xSi coating can significantly improve the wear resistance and oxidation resistance of Ti-6Al-4V alloy.