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The thick Cr coated Zr-4 alloys were prepared by magnetron sputtering deposition and their microstructure evolution and high-temperature air oxidation behaviour were investigated. Oxidation tests showed that the thick Cr coatings can improve the high-temperature air oxidation resistance of Zr-4 alloy even if the α-Zr(O) layer was formed at some regions. The mechanism of high-temperature air oxidation was also discussed in detail, and these experimental results could provide data for establishing a reliable prediction model of this degradation. [ABSTRACT FROM AUTHOR]

The effect of thermal shock temperatures of 1000 °C, 1100 °C, 1200 °C and 1300 °C on the microstructure evolution and adhesion properties of thick Cr coatings on Zr-4 alloy substrates are systematically studied. The results show that the Cr coating has excellent thermal shock resistance even at 1300 °C and still adheres well to the substrate after the thermal shock tests. The main reasons for the degradation of coating properties are the severe diffusion and migration of Cr and Zr at near-eutectic temperatures, while the formation of pores on the Cr 2 O 3 layer may be related to the evaporation of volatile CrO 2 (OH) 2 at the grain boundaries of the Cr 2 O 3 oxides. In addition, the microstructural evolution of thick Cr coatings is also discussed in detail. • The thermal shock performance of thick Cr coating was systematically studied. • The degradation of coating properties was the severe diffusion and migration of Cr and Zr at near-eutectic temperature. • The formation of pores in Cr 2 O 3 layer may be related to the evaporation of volatile CrO 2 (OH) 2. [ABSTRACT FROM AUTHOR]

The amorphous Al 2 O 3 coating with a thickness of approximately 3.3 μm was prepared on ferritic/martensitic steel to investigate the corrosion resistance in contact with static liquid lead‑bismuth eutectic from 100 h to 1000 h at 550 °C. The results showed that Al 2 O 3 coating had poor wettability and could effectively protect the substrate from liquid lead-bismuth eutectic corrosion. However, the structure of the coating changed from an amorphous phase to a dual-phase structure during the corrosion process, leading to the formation of voids. The microscopic corrosion mechanism of Al 2 O 3 coating was also elucidated in detail. • The amorphous Al 2 O 3 coating had poor wettability and could effectively prevent the penetration of liquid LBE. • The structure of the coating changed from an amorphous phase to a dual-phase structure, leading to the formation of voids. • The microscopic corrosion mechanism of Al 2 O 3 coating was elucidated in detail. [ABSTRACT FROM AUTHOR]

The effect of Au-ions irradiation with different damage doses from 10 to 90 dpa on mechanical properties and LBE corrosion behavior of AlCrFeMoTi HEA coating was investigated. The fracture toughness and the interface bonding strength had been improved after irradiation. The Au-ions irradiation decelerated LBE corrosion rate of coating at low damage dose, which could be attributed to the formation of a more continuous Cr 2 O 3 layer adjacent to the coating surface. However, the element diffusion was intensified and the Cr 2 O 3 layer became more thick and porous at high damage dose, which resulted in the acceleration of LBE corrosion. • The amorphous AlCrFeMoTi HEA coatings were irradiated by Au-ions and then exposed to liquid LBE. • The fracture toughness and the interface bonding strength have been improved after Au-ions irradiation. • The Au-ions irradiation decelerated overall corrosion of coating at low irradiation damage dose. [ABSTRACT FROM AUTHOR]

• The (Cr/CrN) 24 multilayer coating was deposited on Zr-4 alloy by magnetron sputtering. • A self-formed ZrO 2 layer in (Cr/CrN) 24 multilayer coating that could protect the substrate to a certain extent. • The decrease of coating performance was due to more O into the coating induced by the diffusion and aggregation of N atoms. (Cr/CrN) n multilayer coatings were prepared on Zr-4 alloy using magnetron sputtering and effects of this multilayer architecture on the microstructure, mechanical properties, surface wettability, high-temperature corrosion and resistance to steam oxidation of the (Cr/CrN) n coating were studied in detail. The (Cr/CrN) n coating designed with a multilayer architecture had excellent high-temperature corrosion resistance. Steam oxidation experiments displayed that the (Cr/CrN) 24 multilayer coating exhibited excellent steam oxidation resistance under high temperature of 1200 °C. Moreover, the oxidation mechanism of the Cr/CrN coating was also discussed intensively. [ABSTRACT FROM AUTHOR]

The amorphous AlCrFeMoTi high-entropy alloy (HEA) coating with near-equal molar ratio was successfully deposited on F/M substrate by magnetron co-sputtering technique and then was irradiated by 6 MeV Au ions with different irradiation damage doses from 10 dpa to 90 dpa. XRD, SEM, AFM, TEM and nanoindentation tests were carried out to investigate the surface morphology, microstructure and hardening effect of the coating. The results showed that the coating surface became more featureless after irradiation, where the surface roughness decreased with increasing damage doses. The crystallization phenomena occurred in amorphous AlCrFeMoTi coatings at high irradiation damage doses (45 dpa and 90 dpa), where the crystallization zone were much closer to the coating surface than the calculated peak damage region. However, the irradiation-induced crystallization did not obviously change the uniformity of elements distribution. Meanwhile, the irradiation hardening effect can be observed, and the nanohardness of the coating increased with increasing damage doses. The AlCrFeMoTi HEA coating exhibits excellent ion-irradiation resistance and has potential applications in lead cooled fast reactor. Meanwhile, this work can help us to further investigate the performance of the AlCrFeMoTi HEA coating in the coupled environment of irradiation and corrosion, and evaluate its serviceability. • The amorphous AlCrFeMoTi HEA coating was prepared by magnetron co-sputtering. • Hardening effect and crystallization were observed after irradiation. • The coating exhibited excellent ion irradiation resistance. [ABSTRACT FROM AUTHOR]

The (HEA/HEAN)-n multilayer coatings consisting of alternating (AlCrFeMoTi)N (top) and AlCrFeMoTi layers were specially designed and successfully deposited on 12Cr2W2Mn F/M steel substrate by reactive magnetron sputtering technology. The dependence of microstructure, mechanical properties and lead-bismuth eutectic (LBE) corrosion resistance on interlayer interface density was systematically investigated. The multilayer structure design improved the mechanical properties and high-temperature structural stability of the multilayer coatings. Furthermore, after exposed to LBE at 650 °C for 1000 h, the (HEA/HEAN)-12 multilayer coatings with optimum interlayer interface density exhibited the most optimal LBE corrosion resistance. The oxidation corrosion mechanism of the (HEA/HEAN)-n multilayer coatings were also discussed intensively. [ABSTRACT FROM AUTHOR]

A refractory TiNbZrMoV high-entropy alloy (HEA) coating was intentionally designed and prepared by magnetron sputtering, and static lead‑bismuth eutectic (LBE) corrosion tests with saturated oxygen were performed to investigate the corrosion behavior of the coatings at 650 °C. The obtained results show that the coating maintained good integrity and significantly mitigated the LBE corrosion of the ferritic/martensitic steel, which originated from the low intrinsic solubility of the coating composition elements and the limitation of element out-diffusion or segregation from the steel and coating. This design of a refractory high-entropy alloy (RHEA) coating provides a novel strategy for the development of LBE corrosion-resistant materials. • A refractory TiNbZrMoV HEA coating was intentionally designed and prepared by magnetron sputtering for LFR. • The coating maintained well structural integrity without apparent segregation or consumption of elements. • The TiNbZrMoV RHEA coating could effectively mitigate the LBE corrosion of the ferritic/martensitic steel. [ABSTRACT FROM AUTHOR]

Al x CrMoNbZr (x = 0, 0.2, 0.4, 1.0, 2.7) multiprincipal element alloy (MPEA) coatings were prepared on Zircaloy-2 (Zr-2) substrates by radio frequency magnetron sputtering. The effects of Al content on the microstructure, mechanical properties and corrosion resistance of the coatings were systematically investigated. The amount of BCC nanocrystals in the as-deposited coatings was found to increase with the addition of Al, leading to an increase in hardness and elastic modulus. Al is found to be a promoting factor for weight gain and oxide layer thickening of the coatings during an autoclave test in static pure water at 360 °C and 18.7 MPa for 45 days, which is related to the vacancies introduced by rapid outward diffusion of Al and slow inward diffusion of O. However, these effects can be ignored when the Al content is low. All the coatings provide superior protection for the Zr-2 substrate due to the inner protective Cr-rich oxide layer adjacent to the coatings. These preliminary screening results provide a criterion and indication for the composition design of Al-containing MPEA coatings applied to accident-tolerant fuel (ATF) claddings. • Al x CrMoNbZr (x = 0, 0.2, 0.4, 1.0, 2.7) MPEAs coatings were prepared by magnetron sputtering method. • The amount of nanocrystals of the as-deposited coatings increase with the increasing Al content. • Al improves the hardness and elasticity modulus of the as-deposited coatings. • The corrosion products mainly consist of an outside Nb 2 Zr 6 O 17 layer and an inside Cr-rich layer. • Al accelerated the corrosion of the coating and the mechanism was disscussed. [ABSTRACT FROM AUTHOR]

• Low Al FeCrAl coatings were prepared on Zr-4 substrates by adjusting deposition bias. • The mechanism of high-temperature steam oxidation and corrosion of FeCrAl coatings was comparatively analysed. • Low Al content was beneficial to enhance the high-temperature steam oxidation and corrosion performance of FeCrAl coatings. FeCrAl coatings with a low Al content were deposited onto Zr-4 substrates by radio frequency magnetron sputtering (RFMS), and the effect of the bias on the microstructure, composition, high-temperature steam oxidation and corrosion properties of the FeCrAl coatings was systematically investigated. Oxidation and autoclave tests showed that the FeCrAl coating with a bias of −150 V (Fe: 80.2 at.%, Cr: 16.7 at.%, and Al: 3.1 at.%) had excellent high-temperature 1000°C steam oxidation and corrosion resistance. The oxidation and corrosion mechanisms are also discussed in detail. [ABSTRACT FROM AUTHOR]

• A novel amorphous AlCrFeMoTi HEA coating was prepared by magnetron co-sputtering method for the LBE-cooled fast reactor. • The coating exhibits excellent LBE corrosion resistance compared with the uncoated F/M steel. • Elemental aggregation, local oxidation and voids appear in the coating when the corrosion temperature reaches 650 ℃. The amorphous AlCrFeMoTi high entropy alloy (HEA) coating with near-equal molar ratio was successfully deposited on F/M substrate by magnetron sputtering method. The coating exhibits excellent corrosion resistance against LBE with much thinner oxides scale and lower consumption of coating compared with the uncoated F/M steel (about an order of magnitude). The AlCrFeMoTi HEA coating has great potential in LBE-cooled fast reactor application. However, the elemental aggregation and local oxidation occur in the coating, and corrosion products of Fe-oxides and voids appear at the interface between the coating and substrate when the corrosion temperature reaches 650 ℃. [ABSTRACT FROM AUTHOR]