Magnetocaloric effect in FeCr soft magnetic nanocrystalline alloys

Abstract In this work the magnetocaloric effect in a Fe 63.5 Cr 10 Si 13.5 B 9 CuNb 3 soft magnetic nanocrystalline alloy is analysed. High resolution transmission electron microscocopy indicates the precipitation of the desired nanocrystalline structure (grains around 10 nm in size surrounded by a residual amorphous phase) upon suitable treatments of the initial amorphous sample. The temperature dependence of the magnetic entropy variation, Δ S M ( T ) , calculated from the magnetization curves displays a maximum negative value around the Curie temperature of the residual amorphous phase ( T C , a ≈ 180 K). The dependence of Δ S M ( T ) on the applied field and its evolution with the nanocrystalline volume fraction indicates the main contribution of the residual amorphous phase to the magnetic entropy change. Some specific low temperature magnetization features (spin freezing) are also analysed in terms of Δ S M ( T ) .