Effect of impurity phase on corrosion resistance and magnetic entropy change for LaFe11.3Co0.4Si1.3C0.15 magnetocaloric compound

Effect of impurity phase (alpha-Fe phase and La-rich phase) on corrosion resistance and magnetic entropy change of LaFe11.3Co0.4Si1.3C0.15 compound was studied using scanning electron microscopy, potentiodynamic polarization, electrochemical impedance spectroscopy techniques and magnetism testing. With the decrease of impurity phase, the corrosion resistance of LaFe11.3Co0.4Si1.3C0.15 compound was first enhanced and then slightly impaired. Corrosion resistance could be significantly improved by the decrease of a-Fe phase. However, the matrix phase was corroded if the La-rich phase as anode was too few. This caused the corrosion resistance to decrease slightly. After immersing the sample in distilled water for 15 d, -Delta S-max of the samples annealed for 3, 12 h, 3 and 7 d decreased about 50%, 41%, 16% and 17%, respectively.