Kinetics of nitridation and wear resistance of titanium alloys

Nitridation kinetics and phase composition in pure titanium as well as in VT22 and NiTi alloys is studied. The thickness of diffusional layers grows with temperature and time of nitridation in NiTi compound the nitridated layer consisting mainly of very hard titanium nitride. Investigation of microhardness distribution about the nitridated layer depth has shown that the sharpest increase of surface hardness occurs in metal NiTi compound, and it is necessary to take into consideration that its nitridation temperature is much lower (500 deg C) than that of titanium and VT22 alloy (900-1000 deg C). Wear tests have shown that wear resistance after nitridation for NiTi compound is several orders higher than that of titanium and VT22 alloy