Modification of Ti-6Al-4V alloy element and phase composition by compression plasma flows impact

Abstract

Phase and element composition, microhardness of Ti-6Al-4V titanium alloy, Ti/Ti-6Al-4V and Zr/Ti-6Al-4V systems treated by compression plasma flows have been investigated in this work. X-ray diffraction, scanning electron microscopy, energy-dispersion X-ray microanalysis and Vickers microhardness measurements were used for samples characterization. The findings showed that treatment of the “coating/titanium alloy” system by compression plasma flows allowed decreasing the toxic elements (Al, V) concentration in the surface layer of Ti-6Al-4V titanium alloy. The variation of the energy absorbed by the surface layer resulted in the change of the element concentration and the formation of a number of phases in the modified layer: a solid solution on the basis of α′ phase in Ti-6Al-4V and Ti/Ti-6Al-4V systems and β phase in Zr/Ti-6Al-4V system. The formation of δ-TiNx at the surface due to interaction of surface layer atoms with nitrogen atmosphere in the vacuum chamber was also found. The change of phase composition and quenching effects resulted in the microhardness increase.