Peritectic Solidification Path of the La(Fe,Si)13 Phase in Dual-Phase Directionally Solidified La-Fe-Si Magnetocaloric Alloys

NaZn13-type La(Fe,Si)13 alloy is a promising magnetocaloric material for solid refrigeration. Currently, several days of high-temperature annealing are typically required to transform both the α-Fe phase and LaFeSi phase to a La(Fe,Si)13 phase by diffusion. However, no bulk casting has yet been reported. In this study, directional solidification is used to prepare LaFe11.6Si1.4 alloys with a dual-phase microstructure consisting of α-Fe and LaFeSi phases. It was found that the volume fraction of La(Fe,Si)13 phase in directionally solidified LaFe11.6Si1.4 alloys can be increased to ~62 pct. It was also found that the volume fraction of the La(Fe,Si)13 phase is dependent primarily on the temperature gradient at different growth rates, which can be the result of their wide temperature range between solidus and liquidus. A significant Si segregation was observed in directionally solidified LaFe11.6Si1.4 alloys. Furthermore, the solidification path was discussed, focusing on the volume fraction increase of the La(Fe,Si)13 phase by directional solidification.