In the last decade high entropy alloys (HEAs) have attracted much attention due to their promising thermomechanical properties, thermal stability and corrosion/oxidation resistance, among others [1,2]. Although many works have been done on the characterization of HEAs from several points of view, radiative properties, i.e. infrared emissivity, of this type of materials are not reported in the literature. The importance of having precise emissivity data of HEAs is twofold. On one hand, these data are crucial for any kind of process optimization and/or for simulations in all applications for which heat is exchanged by radiation. On the other hand, for remote temperature detection (pyrometry or thermography), which is increasingly demanded in online process monitoring, accurate emissivity data are required for calibration.

In the current contribution, the infrared emissivity of a FeCrMnNiCo quasi equiatomic Cantor HEA with a small Ti content has been investigated. Using a dedicated emissometer directional spectral emissivity measurements were acquired as a function of temperature and orientation in the 0.83-25 \mu m wavelength range [3]. The emissivity of the sample decreases monotonically with increasing wavelength. The spectral response remains mostly unchanged for viewing angles smaller than 50⁰ and then increases until reaching its maximum at 80⁰, which is the expected response for metallic materials. The total hemispherical and total normal emissivities determined from directional data in the range 100 – 400 ⁰C. Although both parameters increase with a similar temperature dependence, it is important to note that performing directional experiments is essential to avoid underestimating the radiative behaviour of these materials. Complementarily, microstructural characterization has also been performed after and before emissivity measurements via scanning electron microscopy and x-ray diffraction, and an evolution of the texture has been observed.