Thermal stability and chemical resistance of (Ti,Al)N-Cu and (Ti,Al)N-Ni metal-ceramic nanostructured coatings

•(Ti,Al)N-Cu and (Ti,Al)N-Ni coatings were deposited by the arc-PVD method.•Coatings characterized by the thermal stability up to 700°С.•Coatings characterized by heat resistance at temperatures up to 700 and 800°С.•Study coatings are characterized by relatively high propensity to self-passivation.•Both coatings improve the corrosion resistance of carbide cutting tools. This work represents the results of research on thermal stability, oxidation resistance at temperatures of up to 800°C and electrochemical behaviour of (Ti,Al)N-(∼3 at.%)Cu and (Ti,Al)N-(∼8 at.%)Ni nanocrystalline coatings in acidic and alkaline media. The coatings were deposited by the arc-PVD method with a thickness of approximately 4μm and crystallite size of less than 20nm. It has been demonstrated that the composition and properties of the coating structures do not change when the coatings are heated in 10−4 Pa vacuum at temperatures of 600, 700°C for 1.5h. Heating up to 800°C caused an increase of crystallite size and reduction microstrain in the crystal lattice of the ceramic phase. The process is accompanied by deterioration of the coating hardness from 48 to 52 to 33–36GPa. The (Ti,Al)N-Cu and (Ti,Al)N-Ni metal-ceramic nanostructured coatings are characterized by heat resistance up to the temperatures of 700 and 800°С respectively. The coatings under study have tendency for self-passivation and resistance to pitting corrosion.