A combinatorial study on the influence of elemental composition and heat treatment on the phase composition, microstructure and mechanical properties of Ni–W alloy thin films

Ni–W alloys are promising materials for applications where mechanical stability at relatively high temperature is required. Several Ni–W thin film gradients were synthesized by magnetron sputtering spanning the entire binary composition range. Microstructure and phase composition were characterized by means of X-ray diffraction and transmission electron microscopy, while the mechanical properties were assessed using nanoindentation. As-deposited films exhibit non-equilibrium phases such as amorphous phases in the center of the phase diagram and β-tungsten in the tungsten-rich regime. After annealing, a new X-phase is observed in the center of the phase diagram and non-equilibrium phase compositions are observed for most compositions, such as the presence of α-tungsten at a composition of 75% Ni. Microstructure and composition were successfully correlated to the mechanical properties.