Corrosion behavior and magnetocaloric property of pure phase La1-xCexFe11.5Si1.5 (x=0.1,0.2,0.3) compounds

To further study the corrosion mechanism of pure phase La(Fe,Si)13, Ce were added into the LaFe11.5Si1.5 compounds to facilitate phase formation and improve corrosion resistance and magnetic properties. The corrosion test conducted on the pure phase La1-xCexFe11.5Si1.5 (x = 0.1, 0.2, 0.3) revealed a significant number of minute corrosion pits with irregular shapes such as round, square and triangular after only 1 h of corrosion in tap water. However, in the case of La0.7Ce0.3Fe11.5Si1.5 compound, the number of corrosion pits was significantly lower. Potentiodynamic polarization curves showed that Ecorr goes up from −0.76 V to −0.59 V, and the Icorr goes down from 4.92 × 10−6 A/cm2 to 2.46 × 10−6A/cm2 as a result of Ce addition from 0.1 to 0.3. With the increase of Ce content, the corrosion resistance of La1-xCexFe11.5Si1.5 compounds was improved. Adding Ce element in the LaFe11.5Si1.5 compounds can also enhance the magnetocaloric effect. Significant extra spike-shaped peaks were observed on the M-H curves of La0.8Ce0.2Fe11.5Si1.5 and La0.7Ce0.3Fe11.5Si1.5, indicating a strong first-order magnetic phase transition. Furthermore，-△SM values improved from 21.2 J/kg K to 51.6 J/kg K by increasing Ce from 0.1 to 0.3.