X-ray analysis of the structure-phase states of the Tantalum coating on NiTi substrate treated by electron beams

The evolution of the structural phase states in the Tantalum coatings formed on the NiTi substrate and their change before and after low energy high current pulsed electron beam treatment has been investigated by using X-ray diffraction technique. It was found that in the Tantalum coating reflections of cubic alpha-Ta and beta-Ta tetragonal phases, with a predominance of alpha-Ta phase (similar to 65 vol.%) were observed. The layer between the coating and the NiTi substrate composed of the phase with a bcc structure based on Ta-O with an oxygen concentration of CO approximate to 13 atm.%. After LEHCPEB at E = 15 J/cm2 of coated samples in addition to the B2, alpha-Ta and -Ta phases the martensite phase B19' was detected in the surface layer. It was revealed that after the treatment of samples a uniform layer consisting mainly of Tantalum with no clearly defined boundaries between the coating and the NiTi substrate was formed on the surface. (C) 2015 The Authors. Published by Elsevier Ltd.