Microstructure, fatigue strength and erosion resistance of MAX-phase embedded Ti-Si-B nanostructured coatings on Ti-6Al-4V

Ti-Si-B nanostructured coatings were deposited on Ti-6Al-4V substrates by vacuum plasma processing with droplet separation. A composite Ti-Si-B cathode fabricated by self-propagating high temperature synthesis with subsequent hot pressing was used. The microstructure and mechanical properties of the obtained coatings were analysed by applying Auger-electron spectroscopy, X-ray diffraction and scanning electron microscopy methods accompanied by hardness measurements, fatigue strength and erosion resistance testing. It was established that Ti-Si-B nanostructured coating deposition leads to significant improvement of fatigue strength and erosion resistance of Ti-6Al-4V. A noticeable raise of the fatigue strength is attributed to presence of low dispersed Ti3SiB2 MAX-phase inclusions that suppress fatigue crack propagation.