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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. [ABSTRACT FROM AUTHOR]

The co-influence of B and Si on the formation of 1:13 phase and corrosion behavior of LaFe 13 − x Si x B y alloys is investigated. 1:13 phase is found in as-cast LaFe 11.6 Si 1.4 B 0.5 , while there is no 1:13 phase in as-cast LaFe 12.0 Si 1.0 B 0.5 with lower Si content. The addition of B in the LaFe 13 − x Si x B y alloys is not helpful for the formation of 1:13 phase during the annealing process. B element prefers to form Fe 2 B, rather than occupying interstitial sites in the crystal structure of 1:13 phase, which results in the decrease of the value of magnetic entropy change (| Δ S |). Corrosion behaviors of annealed LaFe 11.6 Si 1.4 B y alloys are reported. The results show that the addition of B improves the corrosion resistance of the alloys. Polarization curves of single phase α -Fe, Fe 2 B and 1:13 phase show that the potential difference between Fe 2 B and 1:13 phase is lower than that between α -Fe and 1:13 phase, which lead to the enhancement of corrosion resistance. The corrosion of LaFe 11.6 Si 1.4 B 0.3 is effectively suppressed, and the value of | Δ S | is only reduced by 28%. [ABSTRACT FROM AUTHOR]