Mechanism of synergistic alloying effects on glass-forming ability of magnetic metallic glasses

Synergistic alloying of Nb and Ni is found to be an effective approach for the pronounced enhancement of glass-forming ability (GFA), in magnetic metallic glasses (MGs), capacitating us to reconcile the long-standing trade-off between GFA and magnetization. By comparing with the commercial FeBPNb and FeNiBSiMo MGs, the Ni and Nb alloying greatly decrease the fragility of the super-cooled liquid and the frequency factor of primary crystallization, which stabilizes the FeNi(B,P,Si)Nb MGs. The Ni and Nb alloying also decrease the liquidus temperature, change the simple primary phases into complicated (Fe,Ni)₂₃(B,P)₆ phases and widen the super-cooled liquid region. The cooperative effects enlarge the structural relaxation window and enhance the pinning effect of clusters in the grain growth process, further deteriorating the kinetic and thermodynamic conditions of the primary crystallization for a better GFA. This synergistic alloying approach can synchronously mediate the driving forces and kinetics, of glass-transition and crystallization, resulting in a multiplicative GFA enhancement effect.