Investigating crystallisation kinetics of Fe$_{40}$Ni$_{40}$P$_{14}$B$_6$ and Fe$_{40}$Ni$_{40}$B$_{20}$ metallic glasses using simultaneous time-resolved quick-EXAFS and XRD

This study employs synchronised multi-edge quick-EXAFS and XRD to resolve the crystallisation kinetics of Fe₄₀Ni₄₀P₁₄B₆ and Fe₄₀Ni₄₀B₂₀ metallic glasses for different heating programs. Time-resolved analysis reveals that Fe₄₀Ni₄₀P₁₄B₆ crystallises via preferential Ni₃P/γ-Fe formation with quick medium-to long-range ordering, while Fe₄₀Ni₄₀B₂₀ follows a slower (Fe,Ni)₃B/γ-FeNi route. Metal-metalloid bonds (Fe-P/Ni-P, Fe-B/Ni-B) exhibit decreasing Debye-Waller factors (σ²) during nucleation, signalling local ordering, while metal-metal bonds (Fe-Fe/Ni-Ni) show mostly increasing σ² due to bond tightness and compositional fluctuations. Heating rates (0.25–2.08 K/s) critically influence the crystallisation onset temperatures (684–867 K), with faster rates delaying the nucleation but preserving phase identity. This work establishes a methodology for correlating short/long-range order dynamics in glass-crystal transitions.