Unraveling the anomalous nano‐crystallization behavior of FeNi‐based amorphous alloy via in situ high‐energy synchrotron X‐ray diffraction

Abstract FeNi‐based MGs exhibit the most excellent room‐temperature mechanical properties among different Fe‐based metallic glasses (MGs) systems. However, the glass‐forming ability (GFA) of FeNi‐based MGs is much lower than that of their counterparts. Thus, uncovering the solidification and anomalous nano‐crystallization behavior of FeNi‐based MGs is crucial to the development of FeNi‐based bulk metallic glasses with larger plasticity and critical size concurrently. Regarding this, a combination of complementary in situ synchrotron radiation high‐energy X‐ray diffraction, small‐angle neutron scattering (SANS), and 3‐dimentional atom probe tomography (3‐D APT) is used to study solidification and nano‐crystallization behavior of Fe 48 Ni 30 Mo 3 B 19 liquid and MG. The time–temperature–transformation diagram was successfully depicted via melting spun, in situ solidification, and isothermal annealing methods. We found that the Fe 48 Ni 30 Mo 3 B 19 MG can only be prepared via the melt‐spinning method to obtain amorphous ribbons, which could contribute to the low activation energy for the nano‐crystallization growth E p . Moreover, during isothermal annealing, the anomalous slow growth behavior in kinetic of the γ‐FeNi phase embedded in the amorphous matrix is caused by the Fe and Ni partitioning, and the Mo‐enriched region around the nanosized γ‐FeNi phase, which is revealed by 3‐D APT. These results exhibit a new perspective for understanding the relationship between GFA and nano‐crystallization behavior and provide feasible guidance for the development of new γ‐FeNi‐containing Fe‐based BMG composites with desired mechanical properties and GFA.