Abstract
A supercooled liquid region before crystallization was found in wide composition ranges of 0 to 65 at%Co and 1.5 to 7 at%Ln in Fe90−xyCoxLnyB20 (Ln=Nd, Sm, Tb or Dy) amorphous alloys. The supercooled liquid region shows the largest value of 41 K for the Fe47Co30Sm3B20 alloy. Besides, an internal equilibrium state leading to the disappearance of the previous thermal history is achieved within a temperature interval of 15 K. Furthermore, the Fe–Co–Ln–B amorphous alloys exhibit soft ferromagnetism with saturated magnetization (Bs) of 0.84 to 1.66 T and coercivity (Hc) of 5.0 to 36 A/m at room temperature. In addition, a high magnetostriction (λs) exceeding 40×10−6 was observed in the composition range of 0 to 10 at%Co and 1.5 to 3 at%Ln (Ln=Sm, Tb or Dy) while the highest λs reaches 58×10−6 for Fe68.5Co10Ln1.5B20 (Ln=Sm or Tb), which is higher than the highest value (44×10−6) for previously reported amorphous alloys. All the Fe68.5Co10Ln1.5B20 amorphous alloys have good bending ductility. The tensile fracture strength, Vickers hardness and Young’s modulus of the Fe68.5Co10Sm1.5B20 amorphous alloy are 3220 MPa, 990 and 76.5 GPa, respectively. The good combination of high λs, high Bs, low Hc, large ΔTx, good ductility and high mechanical strength is a promising new type of ferromagnetic bulk amorphous alloy.