Monolayer Ta and multilayer Ti/Zr/Ta and Zr/Ti/Ta coatings were prepared by magnetron sputtering on TC4 substrates to improve the surface friction and wear properties in a simulated body fluid (SBF) environment and an atmospheric environment. Optical microscopy, scanning electron microscopy, laser scanning confocal microscopy and nano scratch testing were employed to establish the structure-property-environment relationships. By controlling the preparation parameters, the outermost layer of all three samples was Ta coating, and the total coating thickness of each sample was about 3 μm. Friction and wear testing revealed that, compared to bare TC4 substrate, and multilayer Ti/Zr/Ta and Zr/Ti/Ta coatings, the monolayer Ta possessed the lowest friction coefficient as well as the minimum wear rate (i.e., calculation result of the wear track width and wear depth). This was mainly attributed to excellent adhesion strength, a particular structure and solid lubrication of the monolayer coating. The same coating sample exhibited a stronger wear resistance in the SBF environment than in the atmospheric environment. Furthermore, the wear behaviors and mechanisms of various coatings under different experimental environments are also discussed.

In this work, the Ti-20Zr-15Mo alloy in its hot-rolled state was annealed in different phase zones, and the effects of the annealing treatment on the phase composition, organization, mechanical and corrosion resistance properties of the alloy were systematically investigated. The results showed that the original β grains of the alloy had all recrystallized to form the β equiaxial grains when annealed at 800 °C, and the grains had been significantly refined. This allowed the alloy to reach a tensile strength of 1000 MPa, a maximum of 28% after stretching, and a significant increase in plasticity. Also, due to the single beta phase, there was no galvanic corrosion, making the alloy annealed at 800 °C have the best corrosion resistance.

Fatigue crack propagation behaviour of a novel TiZr-based alloy with two different microstructures was studied at room temperature. The measurements at increasing stress intensity factor range were conducted with loading ratios of 0.1 and 0.6. Based on the measurements, it is found that the alloy with the lamellar microstructure shows fatigue striations and secondary cracks. As to the equiaxed microstructure, many facets are generated instead of striations. Compared with the two cases, the alloy with the lamellar structure exhibits a better resistance to fatigue crack propagation, and the resistance increases with a decrease of stress ratio for both microstructures. Combined with electron backscatter diffraction analysis, the lower crack propagation rate of the lamellar microstructure can be ascribed to crack bifurcation and striation growth.