Effect of self-ion with high-energy irradiation on the surface morphology, microstructure and mechanical properties of nanocrystalline TiAlN coating

Abstract

TiAlN coating are used as nuclear reactor cladding protective materials due to their good corrosion resistance. However, long-term exposure to an extremely harsh nuclear environment will cause degradation, and the threshold irradiation fluence is not clear. In this work, a nanocrystalline TiAlN coating was successfully deposited on 304 L stainless steel and silicon wafers by filtered cathodic vacuum arc (FCVA) technology. The effects of different fluences of Al 3+ irradiation performed by the GIC4117 tandem accelerator on the structure and mechanical properties of TiAlN coatings were studied. After irradiation with a fluence of 4.0 × 10 14 ions/cm 2 , the refinement of grain size and columnar structure of nanocrystalline TiAlN coatings was confirmed, which improved the hardness. The irradiation fluence of 4.0 × 10 16 ions/cm 2 reduces all mechanical properties and can be taken as the threshold for the degradation of the TiAlN coating. These nanocrystalline TiAlN coatings have high surface integrity with no destruction, such as flacking, exfoliation and blistering, and good mechanical properties after irradiation. • Ultra-hardness (>40 GPa) was obtained by the formation of nanocrystalline structure and solid solution phase. • The crystallites refined from the average size of 23 ± 2 nm for the initial state up to a size of 18 ± 2 nm. • The hardening effect was confirmed under ion irradiation and the hardness increases from 42.5 ± 1.3 GPa to 46.4 ± 1.4 GPa. • The TiAlN coating with nano-polycrystalline structure exhibits structural integrity without blistering or flaking effects after irradiation.