Influence of the oxidation on the optical properties of Mo-Si-Ti, Ta-Mo-Cr-Al and Ta-Mo-Cr-Ti-Al alloys

Three refractory element-based alloys were oxidized for 6 h at 1100 degrees C in air inside a muffle furnace and the way the oxidation, especially through the evolution of the surface composition and roughness, affects the optical properties of these materials is discussed here. The ternary Mo-20.0Si-52.8Ti (at%) serves as an example of Mobased alloys, while the equimolar Ta-Mo-Cr-Al (TMCA) and Ta-Mo-Cr-Ti-Al (TMCTA) are typical of the class of oxidation-resistant refractory compositionally complex alloys. The normal spectral emissivity of these three samples was increased due to the oxidation process. Oxidized TMCA and TMCTA exhibit a solar absorptivity higher than that of state-of-the-art Ni-based alloys used for solar receivers in concentrated solar power plants. Thus, the two refractory compositionally complex alloys are considered promising candidates for solar thermal energy conversion application.