Magnetic properties of cast Nd60−xFe20Al10Co10Cux alloys

The effect of Cu on the magnetic properties of slowly cooled ${\mathrm{Nd}}_{\text{60−x}}{\mathrm{Fe}}_{\mathrm{20}}{\mathrm{Al}}_{\mathrm{10}}{\mathrm{Co}}_{\mathrm{10}}{\mathrm{Cu}}_x$ $\text{(0⩽x⩽10)}$ bulk amorphous alloys has been studied by room-temperature magnetic measurements. Ferromagnetic bulk amorphous ${\mathrm{Nd}}_{\mathrm{60}}{\mathrm{Fe}}_{\mathrm{20}}{\mathrm{Al}}_{\mathrm{10}}{\mathrm{Co}}_{\mathrm{10}}$ cylinders of 3 mm diameter and 50 mm in length with a coercivity of 298 $\mathrm{kA} {\mathrm{m}}^{\text{−1}}$ were obtained by copper mold casting. The addition of 1 at. % Cu into the ${\mathrm{Nd}}_{\mathrm{60}}{\mathrm{Fe}}_{\mathrm{20}}{\mathrm{Al}}_{\mathrm{10}}{\mathrm{Co}}_{\mathrm{10}}$ alloy causes an increase in coercivity to 321 $\mathrm{kA} {\mathrm{m}}^{\text{−1}}.$ Further addition of Cu by replacing neodymium, however, results in an abrupt decrease in coercivity to 41 $\mathrm{kA} {\mathrm{m}}^{\text{−1}}$ for alloys with $\text{x=10}$ due to the precipitation of a Fe-rich magnetically soft ${\mathrm{Nd(Fe, Co, Al)}}_{\mathrm{2}}$ phase. The improvement of the hard magnetic properties by the addition of 1 at. % Cu for the cast ${\mathrm{Nd}}_{\mathrm{60}}{\mathrm{Fe}}_{\mathrm{20}}{\mathrm{Al}}_{\mathrm{10}}{\mathrm{Co}}_{\mathrm{10}}$ based bulk amorphous alloys may be attributed to an enhanced clustering of Nd–(Fe, Co) pairs in the amorphous alloys.