Effects of transition metal substitution on the glass-formation ability and magnetic properties of Fe_(62)Co_(9.5)Nd_(3)Dy_(0.5)B_(25) glassy alloy

摘要

Fe-Co-Nd-Dy-B glassy alloys are a current type of ferromagnetic material. To increase their glass-forming ability against the growth of a crystallization phase, the effects of the addition of transition metals TM (TM=V, Nb, Ta, Cr, Mo, and W) on the glass-formation ability and magnetic properties of Fe_(62)Co_(9.5)Nd_(3)Dy_(0.5)B_(25) glassy alloy have been investigated. The substitution of 2 at. elements TM (=Nb, Ta, Mo, and W) for Fe and Co increases crystallization temperature Tx and decreases the onset temperature of solidification T_(m), leading to a significant increase in the thermal stability against crystallization for Fe_(60.3)Co_(9.2)TM_(2)Nd_(3)Dy_(0.5)B_(25). The difference (ΔT_(x)=T_(x)-T_(g)) between T_(x) and the glass transition temperature T_(g) increases from 55 K at 0 at. TM to 87 K at 2 at. TM. The bulk glassy alloy with a diameter up to 1.2 mm was produced by copper mold casting. Also no distinct changes in T_(g), T_(x) and ΔT_(x) are seen for the addition of Cr and V. The results can be explained by the difference of atomic size in the additional elements. The saturation magnetization decreases slightly by the addition of 2 at. TM elements. The saturation magnetization and coercive force of glassy Fe_(60.3)Co_(9.2)TM_(2)Nd_(3)Dy_(0.5)B_(25) alloys are 1.13 to 1.19 T and 3.85-4.98 A/m, respectively.