Hard magnetic properties and magnetocaloric effect in amorphous NdFeAl ribbons

Structure and magnetic properties of amorphous melt-spun NdFeAl and subsequently crystallized ribbons were investigated. An amorphous phase was formed after quenching by melt spinning with a copper wheel surface speed of 30 m/s. This amorphous phase exhibited hard magnetic behavior at low temperatures with a Curie temperature of 110 K and a coercivity of 1526 kA/m at 4.2 K. A hexagonal phase with the lattice parameters a = 5.5111 angstroms and c = 8.7448 angstroms was formed in the NdFeAl ribbon after annealing above the crystallization temperature. The magnetic entropy change was calculated directly from isothermal magnetic measurements. The results showed that the amorphous sample had a relatively high magnetocaloric effect, indicating that the amorphous alloy can be considered as a candidate for magnetic refrigeration applications.