Structure of Ti-Ta Alloys Fabricated by Electron-beam Surface Alloying

Abstract

In the present study, Ta coatings with a thickness of 1.7 and 4.2 μm were deposited on Ti samples through reactive magnetron sputtering. The coatings are furthermore treated by a scanning electron beam in order to form the Ti-Ta surface alloy. A change in the phase composition of the Ti-Ta alloy was observed through X-ray diffraction (XRD). The microstructure and the chemical composition of the samples were studied via scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results indicate that in both cases the thickness of the alloyed zone remains the same at about 50 μm. The concentration of Ta in the alloyed zone increases with the increase in thickness of the pre-applied coating. The sample with the 1.7 μm Ta coating has a single-phase hexagonal closed packed structure, corresponding to the \(\alpha \)  phase, whilst the sample with the 4.2 μm coating exhibits a biphasic hexagonal closed-packed structure and a body-centred cubic structure, corresponding to \(\alpha '\) martensitic and β phases.