Experimental study of the isothermal section of the Ho–Fe–Cr system at 873K

The isothermal section of the Ho–Fe–Cr ternary system was investigated by means of X-ray powder diffraction (XRD), metallography and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). The ternary compound HoFe 12− x Cr x ( x = 2) was characterized and the homogeneity range of the various ternary solutions was studied. It crystallizes with ThMn 12 -type structure, space group I 4/ mmm and unit parameters a = 0.8406 nm and c = 0.4756 nm. The homogeneity range in HoFe 12− x Cr x was determined as x = 1.9–3.6, i.e. 14.6–27.7 at.% Cr. The maximum solid solubilities of Cr in Fe, Ho 2 Fe 17 , Ho 6 Fe 23 , HoFe 3 and HoFe 2 are about 28.0 at.%, 4.0 at.%, 13.0 at. %, 3.0 at.% and 11.0 at.%, respectively.