Highly loaded magnetocaloric composites by La(Fe,Si)13H powder dedicated to extrusion-based additive manufacturing applications

Additive manufacturing is attracting increasing interest in the field of magnetic refrigeration to solve the problem of the brittleness of magnetocaloric alloys. The formulation of a composite based on a thermoplastic binder loaded with La(Fe,Si)13H magnetocaloric powder and then its shaping by an innovative additive manufacturing process were investigated in this work. To best preserve the magnetocaloric properties of the powders, the composite must have the highest powder mass fraction and the most suitable rheological behaviour for 3D printing from pellets. The thermorheological characterizations of the powders, the constituents of the binders, the binders and the composites were performed. Except for the powder, these behaviours were modelled as a function of the powder's shear rate, temperature and volume fraction leading to the identification of their different parameters. Criteria encompassing more parameters are defined to select the formulation of the composite with its forming parameters (i.e. from its elaboration to its printing). They lead to the selection of a powder, binder and composite components as well as some process parameters that can be optimised (e.g. maximum powder loading rate, nozzle temperature, shear rate)