Multiscale microstructural evolution of Fe–Ni–Al–Ti alloy with high magnetization

Abstract

The Fe–15Ni–3Al–1Ti ribbons are produced by melt-spinning the annealed ingots at 10–40 m/s. The annealed ingots consist of Fe3Ni grains and α-Fe-type grain boundary phase, forming a columnar grain microstructure in the vertical direction and getting the maximum saturation magnetic polarization (Js) of 1.88 ± 0.03 T in the cross-section. Before and after the annealing, the ribbons form a cellular structure composed of the Fe3Ni intragranular phase and γ-(Fe, M), Fe7Ni3, or α-(Fe, M) cell boundary phases. Formation of enhanced <100> orientation is the primary mechanism for obtaining a high Js of 2.35 ± 0.07 T in the ribbons. The grain and grain boundary size of the ribbons is reduced by the phase transformation induced by annealing at 600 °C. The phase transformation processes of the ribbons before and after annealing are as follows: L→γ→melt−spunFe3Ni+γ1→annealedFe3Ni+Fe7Ni3 when melt-spinning at a speed of 10–25 m/s, and L→γ→melt−spunFe3Ni+Fe7Ni3→annealedFe3Ni+α−(Fe,Ni) at 40 m/s. Finally, the multiscale microstructure evolution models are used to summarize the phase transformation process of the alloys.