Enhanced service properties of a protective coating on a titanium alloy with an ultrafine-grained structure

•Physical-vapor deposited (PVD) coating was applied to Ultra-fine grained (UFG) Ti alloy.•PVD coating improves protective properties and provides higher endurance of UFG Ti alloy.•PVD coating on UFG Ti alloy has large increase in adhesive strength vs. when on coarse-grained alloy.•PVD-coated UFG Ti alloy exhibits high erosion resistance under gas-abrasive wear. The paper presents the results of a study of the service properties of an ion-plasma protective coating deposited on a titanium substrate with an ultrafine-grained structure in the process of Physical vapor deposition (PVD). Data on the microhardness, adhesion strength, and erosion resistance of the ion-plasma coating on the Ti-6%Al-4%V alloy with the initial Coarse-grained (CG) structure and Ultrafine-grained (UFG) state produced by Severe plastic deformation (SPD) are presented. Data were also obtained on the long-term strength of cylindrical specimens in the UFG state with and without coating at the operating temperatures of this alloy. A significant increase in the service properties of the coating on the titanium alloy with an UFG structure was established in comparison with the properties of this coating on the original coarse-grained alloy. The physical nature of the increase in the properties of the coating on the UFG alloy is discussed and a hypothesis about the influence of the UFG state of the substrate on the fine microstructure and properties of the protective coating is considered.