The effect of segregation on the Curie temperature in large-sized La-Fe-Co-Si alloys

Abstract The inhomogeneity of the Curie temperature in large-sized LaFe 13−x−y Co x Si y C 0.15 alloys is studied. The Curie temperature of the large-sized LaFe 13−x−y Co x Si y C 0.15 alloys shows a decreasing tendency from the edge to the sub-edge region of the alloy, while the Curie temperature of the small-sized sheet-shaped LaFe 11.2 Co 0.5 Si 1.3 C 0.15 alloy is same in different regions. Besides, chemical analysis shows that the Co and Si content reveals a decreasing tendency from the edge to the sub-edge region in large-sized alloys as well, which may be attributed to the segregation of Co and Si element during slow solidification in large-sized LaFe 13−x−y Co x Si y C 0.15 alloys. So it can be inferred that the segregation of Co and Si could result in the inhomogeneity of Curie temperature in large-sized LaFe 13−x−y Co x Si y C 0.15 alloys. Moreover, both the experiment and the calculation find that the mixed usage of the inhomogeneous LaFe 13−x−y Co x Si y C 0.15 alloys will reduce the maximum magnetic entropy change, which needs more attention in industrial application of La(Fe 1−x Si x ) 13 based alloys.