Effect of boron on crystallization process, forming ability and magnetic properties of amorphous Fe_91-xZr₅B_xNb₄ alloy

Effects of boron (B) on crystallization, glass forming ability (GFA) and magnetic properties of amorphous Fe_91-xZr₅B_xNb₄ (FZBN) were studied in the B content ranging from 0 to 36 at%. The amorphous FZBN crystallizes to α-Fe in primary crystallization mode at B≤ 20 at% and to Fe-Zr-B-Nb cubic phase with lattice constant of 1.0704 nm and α-Fe in eutectic mode in the range from 22 at% to 30 at% B. The change of crystallization mode is accompanied by the sharp enhance of glass transition and crystallization temperatures. The GFA of FZBN alloys changes with B content and reaches the largest near 27.5 at % B. Curie temperature (T_c) and magnetization at room-temperature (M_RT) and 78K (M_78K) for the amorphous FZBN increase with increasing B content. However, the change laws of the T_c and the magnetizations are somewhat different in the composition ranges of 5 to 20 at% B and 22.5 at% to 30 at% B.