Adiabatic temperature change of micro- and nanocrystalline Y2Fe17 heat-exchangers for magnetic cooling

Magnetic refrigerants are used as heat exchangers to provide rapid heat transfer between magnetocaloric materials and heat-transfer liquid. An important question is how to turn bulk magnetocaloric materials into porous structures with superior heat transfer properties and cooling performance. We discuss two methods for assembling Y2Fe17 rapidly quenched ribbons into heat exchangers of desired geometry stacked 100 mm thick plates with 100 mm gaps: the first method consists in gluing rapidly quenched ribbons using thermoconductive epoxy; the second is sintering stacked ribbons at a temperature of 30 K below the melting point of the Y2Fe17 phase. These approaches are promising with regards to making near-net shaped magnetic refrigerants. We report on adiabatic temperature change Delta T-ad, magnetic entropy change Delta S-m and thermal conductivity lambda of rapidly quenched Y2Fe17 ribbons, obtained at different quenching rates. A direct correlation between the lattice parameters of the Y2Fe17, Delta T-ad and Delta S-m in rapidly quenched samples is observed. (C) 2016 Elsevier B.V. All rights reserved.