Isothermal section of the Ho–Fe–Ga ternary system at 773 K

Abstract

The isothermal section of the Ho–Fe–Ga ternary phase diagram at 773 K was constructed based on X-ray powder diffraction analysis. Fourteen binary compounds and twelve ternary compounds have been confirmed: Ho 2Fe 17 Ho 6Fe 23, HoFe 3, HoFe 2, HoGa 3, HoGa 2, Ho 3Ga 5, HoGa, Ho 3Ga 2, Ho 5Ga 3, Fe 3Ga, Fe 6Ga 5, Fe 3Ga 4, FeGa 3, κ 1-HoFe 6.02–5.24Ga 5.98–6.76, κ 2-HoFe 4.98–4.59Ga 7.02–7.41, κ 3-HoFe 17–14.07Ga 0–2.93, κ 4-HoFe 13.39–8.45 Ga 3.61–8.55, κ 5-Ho 2FeGa 8, κ 6-HoFe 3–2.52Ga 0–0.48, κ 7-HoFe 2.36–1.91Ga 0.64–1.09, κ 8-Ho 2FeGa 8, κ 9-HoFe 2–1.46 Ga 0–0.54, κ 10-HoFe 1.28–1.16Ga 0.72–0.84, κ 11-HoFe 0.43–0.34Ga 1.57–1.66, and κ 12-HoFe 0.26–0.19Ga 1.74–1.81. The maximum solid solubilities of Ga in HoFe 2, HoFe 3 and Ho 2Fe 17 were determined to be 18.1, 11.9 and 15.4 at.%, respectively. The structures of the ternary compounds were refined by Rietveld refinement method. It was shown that all the solid solutions in the ternary system are formed by random distribution of Ga and Fe on the transition metal sites.