Synthesis, microstructure, growth kinetics and oxidation performance of complex concentrated silicide coatings on Nb₇Ti₇Al₁Cr₁ via hot-dip siliconizing

· First-time synthesis of complex concentrated silicide coatings on RCCA alloy using a hot-dipping method. · Coatings deposited via liquid-assisted siliconizing in Al-30Si molten alloy at 850 °C. · Coating thickness increased linearly with time, indicating interfacial reaction-controlled growth. · A 10-minute complex concentrated silicide coating significantly improved oxidation resistance at 1200 °C for 20 hours, with approximately 87% reduction in mass gain. · Demonstrates liquid-assisted siliconizing as a simple, scalable method to enhance high-temperature oxidation resistance of refractory alloys. For different types of materials, particularly those exposed to high-temperatures, applying protective coatings significantly increases their resistance to oxidation. In this study, for the first time, the hot-dip method was used to synthetize silicides-based coatings on a refractory complex concentrated alloy substrate Nb 7 Ti 7 Cr 1 Al 1 . Coatings were applied by dipping the substrates in molten Al-30Si alloy at 850°C for different time periods. Using XRD and SEM/EDS methods aphase, microstructure, and chemical composition of the coatings were analyzed, revealing a primary M(Si,Al)₂ layer. The coating thickness increased linearly with deposition time, indicating interfacial reaction-controlled growth. Notably, a 10-minute coating synthesis significantly improved oxidation performance. Short-term oxidation tests at 1200°C for 20 hours in synthetic air showed linear kinetics for the base alloy, while the coated sample exhibited parabolic behavior and 87% reduced mass gain. These findings demonstrate the potential of liquid-assisted siliconizing for producing oxidation-resistant coatings.