Structure and mechanical properties of quasicrystalline and 2/1 approximant phases in Ti–Zr–Ni coatings

The influence of annealing temperature and annealing time on the structure of coatings with the composition of Ti41Zr41Ni18 (at.%) was analyzed. The conditions for obtaining nanodispersed, single-phase quasicrystalline and 2/1 phase-approximant coatings have been determined. Detailed data about the structure of the films of the little-studied 2/1 approximant phase were collected, using XRD and high-resolution transmission electron microscopy. By nanoindentation, a comparative study of mechanical properties was carried out with samples having different phase compositions. It was established that single-phase coatings of the 2/1 approximant phase are superior to quasi-crystalline ones in terms of hardness and Young's modulus. Coatings of the 2/1 approximant phase reach a hardness of H = 15.42 GPa, Young's modulus of E = 201 GPa at the ratio H/E = 0.077. This allows them to be considered as close to ultra-strong materials.