Structural-phase states and micromechanical properties of nanostructured TiAlCuN coatings

Abstract

TiAlCuN coatings were deposited by reactive magnetron sputtering on substrates of single-crystal silicon, and Titanium Grade2 wafers. To control and manage the coating deposition process by reactive magnetron sputtering, a previously developed modular gas flow control complex (MGFCC) was used. The elemental composition was studied by energy-dispersive X-ray spectroscopy (EDX). The structural-phase state of coatings was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties, such as hardness and Young’s modulus, were investigated by the nanoindentation using a CSM Instruments Nanohardness Tester NHT2 (Switzerland). The influence of deposition parameters such as: Ti and Al content, reactivity degree α, and nitride concentration on structure and mechanical properties was considered. It was found that a decrease in the reactivity degree α from 0.605 to 0.474 leads to a 23 % increase in the deposition rate of TiAlCuN coating. It was detected that adding Cu to the coating content decreases the mean sizes of crystallites and growth columns in comparison with the TiAlN analogues due to its segregation along crystalline boundaries and thus advances better mechanical characteristics. The hardness of TiAlCuN coatings varies in the range of H = 29.3–35.4 GPa, Young’s modulus E = 235.9–267.6 GPa. The impact strength index as the H / E∗ ratio and the plastic deformation resistance index H3 / E∗2 were calculated. The formed nitride coatings are suitable for use in space technologies.