Formation and soft magnetic properties of Co (-Fe)-Si-B-Nb bulk metallic glasses in relation to clusters

Bulk metallic glass formations in Co-based alloy systems are investigated with the guidance of our cluster line approach and minor-alloying principle. Basic ternary alloy compositions in Co-B-Si system are first determined by cluster lines defined by linking special binary clusters to third elements. Then these basic ternary alloys are further minor-alloyed with 4-5 at. % Nb and bulk metallic glasses of 3 mm in diameter are formed in (Co8B3-Si)-Nb, Co8B3 being dense-packed cluster. The bulk metallic glasses are expressed approximately with a unified simple composition formula: (Co8B3)1(Si,Nb)1. Finally a quantity of Fe substitution for Co further improves the glass-forming abilities and these Co-Fe-based quinary bulk metallic glasses have good soft magnetic properties with high saturation magnetization Is, up to 0.98T, and low coercive force Hc, below 6 A/m