Ecomet 250 pro

Samples for the metallographic characterization (A1‐ and A2‐series, Table 1) were embedded in a conductive resin and polished with a SiC abrasive paper and with a diamond polishing solution mixed with a water‐free lubricant (semi‐automatic system, EcoMet 250 pro, Buehler). Microstructural analysis was carried out by optical microscopy (Axioplan 2, Carl Zeiss) and scanning electron microscopy (SEM, Jeol 7800F, Field emission FEG) with an energy‐dispersive X‐ray spectrometer (Quantax 400, Bruker, e⁻ Flash^HR, silicon drift detector). As a result of notable differences in the atomic masses between S and both Fe and In, as well as the possibility of S evaporation from the surface in the electron beam, EDXS yields an unreliable S concentration. Thus, the more accurate wavelength‐dispersive X‐ray spectroscopy method was applied (Cameca SX 100, PeakSight ver. 5.21, Fe K_α, In L_α, S K_α, reference materials: single crystals of FeS₂ and In₂S₃). Determined chemical compositions are presented in Table 1.