Investigation Of Phase Equilibria Of Some Magnetic Alloys

In this paper, the phase relations of the ternary systems in the Fe-Ni-Nb,Fe-Co-Nb, Fe-Ni-Zr, Fe-Ti-Zr and Co-Ni-Zr were measured usingdiffusion-triple together with metallography microscope, scanningelectronic microscope and electronic microprobe analysis techniques(EPMA) etc. Thermodynamic calculation of the Ga-Sc, Ga-Tb and Fe-Ersystem was performed by means of CALPHAD based on the reportedthermodynamic data of relevant and on experimental data, and establish thedatabase of Fe-Cu-Er. Results were shown as folio wings:1. The isothermal section of the Fe-Ni-Nb ternary system at 1198 K hasbeen established, which consists of 5 single-phase fields, 6 two- phasefields and 2 three-phase fields. The three-phase equilibria include:γ(Fe,Ni)+Fe₂Nb+Ni₃Nb and Fe₂Nb+Ni₃Nb+(Fe,Ni)₆Nb₇.2. The isothermal section of the Fe-Co-Nb ternary system at 1173 K has been established, which consists of 7 single-phase fields, 9 two- phase fields and 4 three-phase fields. The three-phase equilibria include:αFe+αCo+Co₃Nb,αFe+Co₃Nb+ Co₂Nb,αFe + Fe₂Nb + Co₂Nb and Fe₂Nb + Co₂Nb+ (Fe,Co)₇Nb₆.3. The isothermal section of the Fe-Ni-Zr ternary system at 1198 K has been established, which consists of 8 single-phase fields, 11 two- phase fields and 5 three-phase fields. The three-phase equilibria include:γ(Fe,Ni)+Ni₇Zr₂+Ni₅Zr,γ(Fe,Ni)+Ni₇Zr₂+Ni₁₀Zr₇,γ(Fe,Ni)+Fe₂Zr+ Ni₁₀Zr₇, (Fe,Ni)Zr₂+Fe₂Zr+Ni₁₀Zr₇, (Fe,Ni)Zr₂+NiZr+Ni₁₀Zr₇.4. The isothermal section of the Fe-Ti-Zr ternary system at 1173 K has been established, which consists of 7 single-phase fields, 7 two- phase fields and 4 three-phase fields. The three-phase equilibria include:β(Ti,Zr)+FeZr₂+FeTi, FeZr₂+FeTi+Fe₂Zr, FeTi +Fe₂Zr +Fe₂Ti, Fe₂Zr +Fe₂Ti +Fe. 5. The isothermal section of the Fe-Ti-Zr ternary system at 1023 K hasbeen established, which consists of 9 single-phase fields, 13 two-phase fields and 7 three-phase fields. The three-phase equilibria include: Fe₂Zr+Fe+Fe₂Ti; Fe₂Zr+FeZr₃+FeTi; Fe₂Ti+FeTi+FeZr₃;αZr+FeZr₃+β(Ti,Zr) ; FeTi+FeZr₃+β(Ti,Zr) ;αTi+βTi+β(Ti,Zr) ; FeTi+βTi+β(Ti,Zr).6. The isothermal section of the Co-Ni-Zr ternary system at 1198 K has been established, which consists of 9 single-phase fields, 14 two-phase fields and 6 three-phase fields. The three-phase equilibria include:α(Co,Ni)+Ni₅Zr+Ni₇Zr₂;α(Co,Ni)+Ni₇Zr₂+Co₂₃Zr₆; Ni₇Zr₂+ Co₂₃Zr₆+Co₂Zr; Co₂Zr+Ni₇Zr₂+NiZr; Co₂Zr+CoZr+NiZr(Co, Ni)Zr₂ +CoZr+NiZr.7. The isothermal section of the Ag-Ti-Zr ternary system at 1023 K has been established, which consists of 7 single-phase fields, 10 two- phase fields and 4 three-phase fields. The three-phase equilibria include: AgTi +AgZr +Ag; AgTi +AgZr + Ag (Ti, Zr)₂;αZr+β(Ti,Zr)+Ag (Ti, Zr)₂;αTi+β(Ti,Zr)+Ag(Ti,Zr)₂.8. Using CALPHAD method, the Ga-Sc,Ga-Tb and Fe-Er binary systems were optimized. Ordinary subitutional solution are adopted to model liquid and other terminal solution, and all intermetallic phases are treated as stoichiometric compounds. Calculated phase diagram and thermodynamic data are both consistent with the experimental work. Then the Fe-Cu-Er system was extrapolated by using the Fe-Er, Fe-Cu and Cu-Er binary systems, and isothermal sections were calculated.