Behaviour of the Young's modulus at the magnetocaloric transition in La(Fe,Co,Si)13

•Magnetocaloric and mechanical properties of La(Co,Fe,Si)13 were investigated.•Flexural strength decreases and Young's modulus increases with Co content.•Reduction of Young's modulus at magnetic transition temperature.•Softening associated with the magnetovolume coupling.

Magnetic solid state cooling applications require families of samples where the magnetic transition is cascaded across the working range of the fridge. Although magnetic properties are widely studied, information relating to the mechanical properties of such systems is less prevalent. Here we study the mechanical properties of a series of magnetocaloric La(Co,Fe,Si)13 samples where the Co content is varied to produce a range of transition temperatures. It was found that at room temperature the flexural strength decreases and the Young's modulus increases with increasing Co content. Interestingly we find a significant reduction of Young's modulus at temperature around the magnetic transition temperature. This reduction was less pronounced with increasing Co content. We associate the softening with the magnetovolume coupling known to exist in these materials.