Magnetic and magnetocaloric properties of R55Co30Al10Si5 (R = Ho, Dy) metallic glass ribbons

Abstract

Metallic glass alloys are suitable systems for the development of magnetocaloric refrigerated materials due to the stable physical properties and the adjustable magnetic phase transition temperature. Here, the glass formation ability (GFA), magnetic properties and magnetocaloric effects of R55Co30Al10Si5 (R = Ho, Dy) amorphous ribbons prepared by the melt-spinning technique were investigated. The X-ray diffraction and DSC measurement indicated that the metallic glass alloys have a completely amorphous structure and excellent glass formation ability. The amorphous ribbons were demonstrated to undergo a second-order magnetic phase transition (ferromagnetic to paramagnetic) around Tc ∼ 18 K for Ho55Co30Al10Si5, ∼34 K for Dy55Co30Al10Si5, respectively. The maximum magnetic entropy change (-ΔSMmax) and the corresponding refrigerant capacity (RC) values are 12.7 J/kg K, 343 J/kg for Ho55Co30Al10Si5, 9.1 J/kg K, 334 J/kg for Dy55Co30Al10Si5 under a field change ΔH= 5 T. The large -ΔSMmax and high RC suggest that R55Co30Al10Si5 (R = Ho, Dy) amorphous ribbons have potential applications in low temperature magnetic refrigeration.