Negative thermal expansion (NTE) is an unusual yet highly useful phenomenon that has been extensively studied in numerous crystals, including ceramics, alloys, and metal-organic frameworks. This Letter reports an unprecedented NTE in an amorphous ${\text{Fe}}_{87.5}{\mathrm{Y}}_3{\text{Zr}}_{1.5}{\mathrm{B}}_8$ alloy that lacks a periodic atomic arrangement. Such an NTE is significant for metallic materials and extends over a wide temperature range (${\alpha }_1=-6.9\times {10}^{-6}{\mathrm{K}}^{-1}$, 200–375 K). We demonstrate that this NTE is intrinsic to the amorphous nature of the alloy and is correlated with Fe moment. Extended x-ray absorption fine structure reveals a strong NTE for nearest neighboring Fe-Fe pairs. Further analysis using a x-ray pair distribution function indicates that the amorphous ${\mathrm{Fe}}_{87.5}{\mathrm{Y}}_3{\mathrm{Zr}}_{1.5}{\mathrm{B}}_8$ alloy, serving as a transition state, exhibits a tendency toward local ordered atomic arrangement. A complex interplay among local structure, magnetic interaction, and thermal relaxation results in volume contraction upon heating below $T_C$. This Letter introduces amorphous alloys as a new family of materials with NTE functionality, offering interesting prospects for both scientific research and practical applications.

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• Magnetic order
• Thermal expansion
• Metallic glasses
• X-ray absorption fine structure spectroscopy
• X-ray pair-distribution function analysis