Evolution of microstructure and macrostress in sputtered hard Ti(Al,V)N films with increasing energy delivered during their growth by bombarding ions

This letter reports on the effect of the energy E_bi, delivered to the sputtered Ti(Al,V)N film by bombarding ions, on its microstructure, macrostress σ, mechanical properties, and resistance to cracking. The films were deposited by reactive magnetron sputtering. Interrelationships between these parameters were investigated in detail. It was shown that (1) the increase of the energy E_bi makes it possible to convert (1) the film microstructure from columnar to dense, noncolumnar, (2) the macrostress σ from tensile (σ > 0) to compressive (σ < 0), (3) the brittle hard film with low ratio H/E^*< 0.1 and low elastic recovery W_e < 60% to the flexible hard film with high ratio H/E^*≥ 0.1 and high elastic recovery W_e ≥ 60%, (2) the flexible hard Ti(Al,V)N films with high ratio H/E^*≥ 0.1, high elastic recovery W_e ≥ 60%, and compressive macrostress can be formed not only in the transition zone (zone T in which the films exhibit a dense, voids-free microstructure) of the Thornton's structural zone model (SZM) but also in zone 1 in which the films exhibit a columnar microstructure and (3) the line corresponding to the films with zero macrostress (σ = 0) in the SZM lies in zone 1 corresponding to the columnar microstructure; here, H is the film hardness and E^*= E(1 − ν²) is the effective Young's modulus, E is the Young's modulus, and ν is the Poisson's ratio.