Effect of excess lanthanum on corrosion and magnetocaloric property of LaFe11.5Si1.5 compounds

• Published in: Journal of rare earths Vol. 37; no. 10; pp. 1116 - 1120
• Main Authors: Hu, Jie, Dong, Zhongqi, Shen, Yingming, Fu, Bin, Zhang, Bianfang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2019
• Subjects: Corrosion; Magnetic materials; Magnetocaloric; Rare earths; Magnetic materials; Magnetocaloric; Corrosion; Rare earths
• ISSN: 1002-0721; 2509-4963
• DOI: 10.1016/j.jre.2019.01.007

The corrosion and magnetocaloric property of LaFe11.5Si1.5 compound with excess La from 0 wt% to 15 wt% were investigated by a scanning electron microscope (SEM), electrochemical workstation and a vibrating sample magnetometer (VSM). With the increase of excess La from 0 wt%, 5 wt% to 10 wt% and 15 wt%, most of the La-rich phase changes from granular La2O3 phase to grain boundary LaFeSi phase. The La2O3 is more stable than the main 1:13 phase, while LaFeSi phase is easy to be corroded than the 1:13 phase. The maximum entropy change −ΔSmax is 18.60, 21.48, 19.66 and 16.28 J/(kg·K) for 0 wt%, 5 wt%, 10 wt% and 15 wt% excess of La, respectively. As adding 5 wt% excess La in LaFe11.5Si1.5 compound leads to nearly single 1:13 phase, the largest magnetic entropy change and better corrosion resistance are obtained. With the increase of excess La from 0 wt% (a), 5 wt% (b) to 10 wt% (c) and 15 wt% (d), most of the La-rich phase changes from granular La2O3 phase to grain boundary LaFeSi phase. The La2O3 is more stable than the main 1:13 phase, while LaFeSi phase is easy to be corroded than the 1:13 phase. The corrosion of each phase increases in the order: LaFeSi > La(Fe,Si)13 > La2O3 > ɑ-Fe. [Display omitted]