Study on the magnetic properties and coercivity mechanism in the [Nd_(0.7)Pr_(0.3)]_(60-x)Fe_(30)Al_(10)Dy_x(x=0,1,2) bulk amorphous alloys

Bulk amorphous( Nd0. 7Pr0. 3)60-x Fe30Al10Dy x( x=0,1,2) alloys of 2 mm in diameter were prepared by argon arc melting and suction casting the molten alloy into a copper mould. The magnetic properties of the alloys,including major hysterisis loops,the field dependence of the irreversible susceptibility,exchange coupling curves( δM-H plot) and the temperature dependence of the coercivity,were investigated by vibrating sample magnetometer( VSM). The results indicated that each alloy sample exhibited hard magnetic behavior. With increasing Dy content,the residual magnetisation and saturation magnetisation changed slightly while the coercivity was enhanced apparently. The exchange coupling interactions in these alloys were confirmed by the δM-H plots. The temperature dependence of the coercivity was well explained by Gaunt 's strong pinning model of domain walls. The hard magnetic behavior of bulk amorphous( Nd0. 7Pr0. 3)60-x Fe30Al10Dy x( x=0,1,2) alloys may be attrituted to the effect of exchange coupling interaction among clusters and the strong domain wall pinning mechanism.