Environment-assisted crack nucleation in La(Fe,Mn,Si)13-based magnetocaloric materials

Cracking in La(Fe,Si)13-based magnetocaloric materials has been observed to predominantly form around La-rich (La2O3) particles and pose a threat their long-term structural integrity. To understand the formation of these cracks, FIB cross-sectional polishing followed by SEM characterisation was employed study local microstructural evolution after air exposure. Results suggest that volume expansion internal degradation associated with chemical reaction between La2O3 water/moisture can lead crack nucleation 1:13 phase adjacent particles. This observation indicates should be suppressed, or size minimised during material processing ensure integrity La(Fe,Mn,Si)13 materials.