Corrosion behavior and phase formation of LaFe13−xSixBy alloys

Abstract The co-influence of B and Si on the formation of 1:13 phase and corrosion behavior of LaFe13 − xSixBy alloys is investigated. 1:13 phase is found in as-cast LaFe11.6Si1.4B0.5, while there is no 1:13 phase in as-cast LaFe12.0Si1.0B0.5 with lower Si content. The addition of B in the LaFe13 − xSixBy alloys is not helpful for the formation of 1:13 phase during the annealing process. B element prefers to form Fe2B, 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 (| ΔS |). Corrosion behaviors of annealed LaFe11.6Si1.4By 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, Fe2B and 1:13 phase show that the potential difference between Fe2B 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 LaFe11.6Si1.4B0.3 is effectively suppressed, and the value of | ΔS | is only reduced by 28%.