(W, Ta, Mo, Cr)(Al, Si)2-Al2O3 dual-phase high-entropy alumino-silicides with superior oxidation resistance up to 2100 °C

High-temperature materials with superior long-term oxidation resistance above 2000 °C are urgently sought for next-generation hypersonic vehicles. Here, (W 0.28 Ta 0.28 Mo 0.28 Cr 0.15 )(Al 0.2 Si 0.8 ) 2 -Al 2 O 3 dual-phase high-entropy alumino-silicides (HEAS-Al 2 O 3 ) are developed, which exhibit superior long-term oxidation resistance up to 2100 °C. To be specific, the as-fabricated HEAS-Al 2 O 3 samples are found to consistently follow an oxygen-diffusion parabolic law across 1700–2100 °C, possessing a high activation energy of 234.4 kJ mol −1 . Moreover, an ultralow oxidation depth of 0.4 mm after 120 min of laser oxidation and a linear plasma ablation rate of 0.026 μm s −1 at 2100 °C are achieved. Such remarkable oxidation resistance is mainly attributed to the increase in Al cations due to Al 2 O 3 incorporation, coupled with the inclusion of multiple cationic elements, to significantly enhance the rigidity of the glass network. Thereby, the viscosity and high-temperature stability of the resulting aluminosilicate glass are markedly improved, effectively protecting the underlying unoxidized HEAS-Al 2 O 3 . The as-developed HEAS-Al 2 O 3 shows great promise as a thermal structural candidate for next-generation hypersonic vehicles.