Structure and Mechanical Properties of TiAlN Coatings under High-Temperature Ar+ Ion Irradiation

Abstract

Using the method of reactive magnetron sputtering, nanostructured TiAlN coatings were formed on the substrates of AISI 304 stainless steel. The formed TiAlN coatings were irradiated with argon ions Ar+ with an energy of 200 keV in the fluence range from 2.5 × 1016 ions/cm2 to 2 × 1017 ions/cm2 at a temperature of 480◦C. The elemental composition and structural-phase state of virgin and irradiated coatings were investigated by methods of energy-dispersive X-ray spectroscopy, scanning electron microscopy as well as X-ray phase analysis. The mechanical properties of the obtained structures were studied by nanoindentation using the Oliver and Pharr method; hardness and Young’s modulus were measured. The indicators of the impact strength, as the H/E∗ ratio, as well as the resistance to plastic deformation, as the H3/E∗2 ratio, of the coatings under study were calculated. It was found that the nanostructured TiAlN coatings retain their structure up to the irradiation fluence of 2 × 1017 ions/cm2, at which the beginning of phase segregation of solid solution (Ti, Al)N as the main phase of the coating as well as blistering is observed. The nonlinear nature of changes in the hardness H, Young’s modulus E, impact strength H/E∗, and resistance to plastic deformation H3/E∗2 on the irradiation fluence was found.