Abstract
The AlNbTiZr medium-entropy alloy (MEA) coatings with different Al contents were prepared on N36 zirconium alloy substrates by RF magnetron co-sputtering. The morphology, microstructure, mechanical properties, surface wettability and corrosion resistance of the AlNbTiZr MEA coatings were studied to evaluate the surface protection behavior of zirconium alloy cladding under operation conditions of a pressurized water reactor. The results showed that all the coatings were composite structures with amorphous and bcc-structured nanocrystals. With the increase of Al content, both the elastic modulus and hardness decreased first and then increased. The hydrophobicity of the coatings was enhanced compared with that of the substrate. The 10.2 at.% Al AlNbTiZr coating had the best corrosion resistance and the minimum oxygen penetration depth, which originated from the formation of a denser oxide layer consisting of Nb2Zr6O17 and ZrO2. This study provides an improved idea for the design and development of Al-containing MEA coating materials for accident tolerant fuel.
Highlights
After the Fukushima nuclear accident, scientists have carried out extensive research on accident tolerant fuel (ATF) projects for pressurized water reactors (PWRs) [1]
The five AlNbTiZr medium-entropy alloy (MEA) coatings with different Al content were deposited on singlecrystalline silicon wafers and N36 Zr alloy (Zr-1Sn-1Nb-0.3Fe in wt.%) substrates by RF
The contents of the Nb, Ti and Zr in AlNbTiZr MEA coatings remained approximately equal in molar ratios
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The second one is to prepare protective coatings on the surface of zirconium alloy cladding to ameliorate its high-temperature oxidation resistance, mainly representing metallic coatings (Cr, Mo, CrAl, FeCrAl, high entropy alloy, etc.) [11,12,13,14], ceramic coatings (CrC, SiC, CrN, MAX phase materials, etc.) [15,16,17,18,19,20] and composite coatings (Cr/CrN, TiN/TiAlN, etc.) [20,21] Based on these results, the above coatings exhibit excellent corrosion resistance in hightemperature pressurized water experiments, it is still an important topic to exploit new candidate coatings that can withstand LOCA accidents in PWR. The effect of Al content on the microstructure, wettability, mechanical properties and corrosion resistance of the AlNbTiZr MEA coatings were systematically evaluated
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