Effect of chromium on magnetic properties and corrosion resistance of LaFe11.5Si1.5 compound

Effects of Cr addition on magnetic and corrosion properties of LaFe11.5-xCrxSi1.5 (x=0.1, 0.3, 0.4) magnetic refrigerants were investigated. It was found that the addition of Cr slightly decreased the magnetic entropy change, but it was effective in increasing corrosion resistance of La-Fe-Si compounds within the composition range examined. Corrosion measurements showed that corrosion current density of these La-Fe-Si compounds in distilled water decreased from 2.6×10−6 to 8.7×10−7 A/cm2, with x increasing from 0 to 0.3, while magnetic entropy change in LaFe11.5-xCrxSi1.5 compounds did not change significantly (−ΔSmax was 18.0, 17.0, 13.6, 11.1 J/(kg·K)) under 2 T for x=0, 0.1, 0.3, 0.4, respectively). Surface optical microstructures of compounds after corroded showed that corrosion took place at grains and grain boundaries simultaneously and surface concentration of corroded points on LaFe11.5-xCrxSi1.5 (x=0.1, 0.3, 0.4) compounds reduced obviously.