Radiation tolerance of nanostructured TiAlN coatings under Ar+ ion irradiation

The radiation tolerance of TiAlN coatings under irradiation with 200 keV Ar+ ions is studied at room temperature. The ion fluence varied in the range of 1.10(16)-2.10(17) ions/cm(2). The TiAlN coatings were deposited by reactive magnetron sputtering on single crystalline silicon wafers as well as on AISI 304 stainless steel bars. Elemental composition of the coatings was investigated using Rutherford backscattering spectrometry with He+ ions of 2.53 MeV and 4.53 MeV as well as by energy-dispersive X-ray spectroscopy using 18 keV electrons. Phase composition and structure of TiAlN coatings were examined by X-ray diffraction and scanning electron microscopy. Mechanical properties of TiAlN coatings were evaluated by nanoindentation using a nanohardness tester with a Berkovich diamond tip and applying the Oliver-Pharr method. Some selective nitrogen sputtering was detected caused by the Ar+ ion irradiation. The TiAlN coatings crystallites refined under argon ion irradiation. It was found that the irradiation fluence of 2.10(17) ions/cm(2) is a threshold fluence, at which the solid solution decomposition starts. Ion irradiation causes mechanical properties improvement up to the fluence of 5.10(16) ions/cm(2). No destruction processes of the coatings such as blistering or flaking were detected for all irradiation fluences used in this study.