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.