Enhancing mechanical properties and tribocorrosion resistance of TC4 alloys via plasma nitriding

TC4 alloys were nitrided in N2: Ar plasma by a nitriding furnace to improve the hardness and tribocorrosion resistance of the titanium alloy. The effect of nitriding temperature on the microstructure and properties of the TC4 alloy was elucidated. The results show that with an increase in the nitriding temperature, the hardness and elastic modulus of the nitrided TC4 alloy as well as the thickness of the nitriding layer increase. Compared with untreated TC4, the nitrided TC4 alloys exhibit better mechanical properties, corrosion resistance, and tribocorrosion resistance due to the formation of α-Ti(N), Ti2N, and TiN. Therein, the tribocorrosion rate of the TC4 alloy at a nitriding temperature of 800 °C decreases to 1.66 × 10−5 mm3/(N m), decreased by 89.4% over untreated TC4 alloy. The enhancement in tribocorrosion properties of the nitrided TC4 alloy is attributed to the presence of nitride with high hardness and tribochemical reaction at the interface between Si3N4 and the matrix.