Phase Composition, Microstructure, Surface Hardness, and Corrosion Resistance of Surface Plasma Gas Nitrided Titanium Alloy Ti-10V-2Fe-3Al with Indirect Plasmatron

Abstract

This study investigates and analyzes the influence of plasma gas nitriding with indirect plasmatron on the phase transformations, microstructure, surface microhardness, and corrosion resistance of titanium alloy Ti-10V-2Fe-3Al. In order to achieve this, the limits of the power used in this process are a minimum of 12 kW and a maximum of 35 kW. The thermochemical treatment time intervals are set at 5, 10, and 15 min. It is found that the phase composition of the surface layer after plasma gas nitriding consists of α-Ti, (N, O), TiN, and TiO2. Titanium oxides are detected only on the outermost surface of the nitrided layers. The measured hardness of the plasma gas nitrided layers obtained of Ti-10V-2Fe-3Al is up to 650 HK0.05. Potentiodynamic polarization analysis indicates that the subjects nitrided using 18 kW of power for 15 min have the lowest corrosion rate, while the highest corrosion rate is observed in those nitrided at 25 kW for 15 min.