Ion-induced phase transformations in nanostructural TiZrAlN films

摘要

(Ti,Zr)_(1-x)Al_xN_y thin films (300 nm) with Ti:Zr ratio of ~1:1 and Al content in metal sublattice up to x= 0.312 were deposited at T_s=270 °C using reactive unbalancedmagnetron co-sputtering in Ar+N2 plasma discharges. The nitrogen content, y, was understoichiometric when x ≥ 0.102, despite constancy of N_2 partial pressure used during growth. The influence of Xe ion irradiation (180 keV, 1 × 10~(15) -1 × 10~(17) cm~(-2)) on the structure, phase formation and mechanical properties of the filmswas investigated. The increase in Al content resulted in gradual evolution of the microstructure from single-phase, nanocrystalline cubic (c) solid solution (x ≤ 0.072) to dualphase nanocomposite (x = 0.102-0.200) and then to amorphous (x = 0.312) one. Nanocrystalline and amorphous films were stable under irradiation, while crystallization occurred in nanocomposite films for a typical ion fluence of 1 × 10~(16) cm~(-2). This phase transformation is associated with the reduction of compressive stress and eventually leads to the development of a net tensile stress inside crystallites. For all films, a decrease of the nanoindentation hardnesswas observed after an ion fluence of 5 × 10~(16) cm~(-2), likely related to the incorporation of Xe impurities, as revealed by RBS data.