Characterization of Ti–6Al–4V alloy modified by plasma carburizing process

In order to strengthening the surface of the Ti–6Al–4V alloy, plasma carburizing technique was carried out, although plasma nitriding has been more widely used for its alloy. The alloy was carburized at 900 °C and 250 MPa for 21.6 ks using plasma of 17 vol.% CH4–Ar–H2 gas. For reducing the impurity effect on the carburization, surface was cleaned by H2–Ar gas at 1100 °C. The reacted zone was examined by using optical microscopy and Grazing X-ray diffractometer (GXRD) as well as by hardness testing. The mechanical properties such as wear and fatigue were evaluated and compared with the untreated alloy. The hard carbide particles, TiC and V4C3, were observed to form throughout the carburized layer thickness of 150 μm, and contributed to improve the mechanical properties at both room and elevated temperature. Fracture mode was also examined.