Corrosion behavior and magnetocaloric property of pure phase La 1-x Ce x Fe 11.5 Si 1.5 (x=0.1,0.2,0.3) compounds

To further study the corrosion mechanism of pure phase La(Fe,Si) , Ce were added into the LaFe Si compounds to facilitate phase formation and improve corrosion resistance and magnetic properties. The corrosion test conducted on the pure phase La Ce Fe Si (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 La Ce Fe Si 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 A/cm to 2.46 × 10 A/cm as a result of Ce addition from 0.1 to 0.3. With the increase of Ce content, the corrosion resistance of La Ce Fe Si compounds was improved. Adding Ce element in the LaFe Si compounds can also enhance the magnetocaloric effect. Significant extra spike-shaped peaks were observed on the curves of La Ce Fe Si and La Ce Fe Si , indicating a strong first-order magnetic phase transition. Furthermore，-△ values improved from 21.2 J/kg K to 51.6 J/kg K by increasing Ce from 0.1 to 0.3.