ENHANCING THE WEAR RESISTANCE OF Ti-6Al-4V ALLOY THROUGH ELECTRON BEAM ASSISTED OXYGENATION

Irradiation with a low-energy, high-current electron beam of microsecond duration was shown to substantially enhance the tribological properties of Ti-6Al-4V alloy. Irradiation was carried out in the two modes: at ambient (300 K) and elevated (823 K) temperature. Auger electron spectroscopy showed that irradiation at ambient temperature results in cleaning the surface layer from the dissolved atmosphere gases oxygen and carbon. However, the wear resistance of titanium alloy irradiated at ambient temperature was found to be worse than that for the non-irradiated one. In contrast, a high fraction of oxygen in the surface layer of a specimen irradiated at the elevated temperature was revealed. The high fraction of dissolved oxygen was established to induce the phase transition in the surface layer and occurrence of omega-phase of titanium having the enhanced mechanical properties. The wear resistance of titanium alloy irradiated in this mode is more than fifty times as much as the non-irradiated one. Convectional aging of the titanium alloy at 823 K leads to occurrence of an oxygen solid solution in titanium without essential increasing the wear resistance