Improvement of Ti-6Al-4 V alloy in terms of mechanical and tribological properties by oxidation and nitriding

Abstract

In this study, we aimed to compare the mechanical properties and tribological properties of specimens after different thermal treatments. We treated specimens in oxidation and nitriding with argon in the chamber with 900 °C and 950 °C respectively. The results of the microhardness showed that the oxidized specimens were observed the highest value of 788VHN (0.05). We found that comparing to oxidized specimens (CoF=0.6 ± 0.09), the nitrided specimens showed lower coefficient of friction (CoF=0.52±0.06). There was around two times improvement of microhardness comparing to untreated specimens. And oxidized specimens (1.61±0.29 μm3/Nmm) showed five times lower value of wear rate than nitrided specimens (4.12±0.79 μm3/Nmm), and around ten times lower value of wear rate than nitrided with mechanic pump (9.54±0.68 μm3/Nmm). We concluded that oxidation could help to achieve the enhancement of hardness and wear properties, but with thinner layer on the surface. Nitriding with diffusion pump increased the efficiency of Ar+ and N+ diffusion than only with mechanic pump.