Ni-free superelastic binary Ti-Nb coatings obtained by DC magnetron co-sputtering

Ni-free superelastic binary Ti-Nb coatings are obtained by co-sputtering of pure Ti and Nb metallic targets. The aim is to investigate the composition dependence of the beta-phase stabilization and mechanical properties (i.e. Young's modulus, hardness and depth recovery) of Ti-1 (-) Nb-x(x) thin films. The beta-phase is detected when the concentration of niobium is above 17 at.% and the films are beta-single phased above 34 at.% Nb. The preferential orientation of the beta-phase is {110} and it becomes {111} at high niobium contents, which may be due to the competition between surface and strain energies and anisotropy collision effect The fully beta-phase coating presents high depth recovery, which is due to the superelastic effect attributed to stress-induced martensitic transformation. (C) 2015 Elsevier B.V. All rights reserved.