Magnetic properties and crystallization of the rapidly quenched (Fe 1- x Nd x ) 81.5 B 18.5 alloys

Abstract

Magnetic properties and crystallization behaviors of amorphous (Fe1-xNdx)81.5B18.5 alloys were studied. The crystallization temperature is found to rise at first and then drop monotonically with x, having a maximum value of 976 K at x = 0.11 (9 at% Nd). The (Fe1-xNdx)81.5B18.5 alloys prepared at a quenching rate of vs = 6.6 m/s are amorphous, and exhibit good glass formability. Both the coercive field Hc and energy product (BH)max depend strongly on Nd concentration. Amorphous (Fe1-xNdx)81.5B18.5 alloys with higher Nd concentration have a high coercive field at low temperature, due to the large random uniaxial anisotropy of Nd. The room-temperature Hc and (BH)max obtained on optimal annealing conditions show two maxima as a function of Nd concentration x. The highest room-temperature coercive field Hc = 22 kOe within the Nd concentrations around x = 0.368 and the maximum energy product (BH)max = 13.3 MG Oe at x = 0.055 are observed. The hard magnetic properties of these crystallized samples are related to the presence of the hard magnetic Nd2Fe14B phase.