Formation and magnetic properties of bulk glassy Fe-Co-Nd-Dy-B alloys with high boron concentrations

Abstract

New Fe-based glassy alloys in Fe-Co-Nd-Dy-B system with high boron concentrations were found to exhibit a wide supercooled liquid region exceeding 50 K. The high stability of the supercooled liquid enabled us to produce cylindrical bulk glassy alloys with diameters up to 0.75 mm by copper mold casting. The glass transition temperature (T g ), crystallization temperature (T x ), supercooled liquid region ΔT x (=T x - T g ) and heat of crystallization of the Φ0.75 mm rod of glassy Fe 62 Co 9.5 Nd 3 Dy 0.5 B 25 alloy are 844 K, 899 K, 55 K and 4.46 kJ/mol, respectively. No appreciable difference in the thermal stability is seen between the bulk rods and melt-spun ribbon. The saturation magnetization (I s ), coercive force (H c ), saturated magnetostriction (λ s ) and Curie temperature (T c ) of the melt-spun Fe 62 Co 9,5 Nd 3 Dy 0.5 B 25 ribbon are 1.37T, T, 4.58 A/m, 17.9 × 10 -6 and 663 K, respectively, and I s and T c are nearly the same as those for the bulk glass rods with diameters of 0.5 and 0.75 mm. The success of forming the Fe-based bulk glassy alloys exhibiting good soft magnetic properties is promising for future development as a new type of soft magnetic material.