Corrosion behavior of magnetic refrigeration material La-Fe-Co-Si in distilled water

Research highlights: → In this paper, we study the corrosion behavior of La(Fe0.94Co0.06)11.7Si1.3 compound in distilled water and report an unexpected discovery that corrosion occurs at matrix phase rather than rare earth rich phase, which is different from other rare earth materials. The corrosion has decreased the maximum magnetic entropy change of the compound. - Abstract: The corrosion behavior of magnetic refrigeration material La(Fe0.94Co0.06)11.7Si1.3 in distilled water has been studied using X-ray diffraction analysis, weight loss method, scanning electron microscopy and X-ray photoelectron spectroscopy. Results show that La(Fe0.94Co0.06)11.7Si1.3 compound suffers electrochemical preferential corrosion in distilled water. La(Fe0.94Co0.06)11.7Si1.3 compound contains three phases which are matrix phase, a small amount of α-Fe phase and La-rich phase. The matrix phase with NaZn13 structure works as anode to be corroded. The final corrosion products on sample surface are La2O3, γ-Fe(OOH), Co(OH)2 and H2SiO3, respectively. Corrosion has decreased the maximum magnetic entropy change of the compound.