Microstructure, phase composition and hardness of Ti–Au cladding deposited on Ti–6Al–4V substrate by electron beam powder bed fusion method

Abstract

In this study, a Ti–Au cladding was deposited on a substrate from the Ti–6Al–4V alloy by the electron beam powder bed fusion method in a vacuum. The main goal was to assess the possibility of using titanium powders and gold foils as a feedstock for additive manufacturing of such dental products. The microstructure, chemical element distributions, phase composition and hardness of the formed Ti–Au alloy were studied using optical microscopy, energy dispersive X-ray analysis, as well as X-ray diffraction and nanoindentation tests. Gold-containing intermetallic compounds were observed through the entire cladding thickness. The α-Ti, α-Au, AuTi and AuTi3 phases were found, in addition to the Ti3Au one, which provided hardness values greater than those of conventional titanium alloys. It was shown by results of the crystal-geometric and X-ray phase analysis that the AuTi3 phase possessed the most densely packed A15 structure. This fact correlated with the obtained data on the deviation of the atomic volume per ion from Zen's law and the high hardness levels. Metallurgical patterns of the microstructure formation that affected the functional properties of such claddings were discussed and a further research direction was proposed.