Pinning of nanocrystals growth at Fe–Ni–B amorphous alloy crystallization: Atom probe investigations

• The phenomenon of crystal growth pinning during annealing was found by TEM.
• The formation of the barrier layer enriched in Boron was found by 3DAP.
• The phenomenon can be described by “Crystallization-and-stop” model.

The crystallization processes in Fe50Ni33B17 amorphous alloy have been investigated by transmission electron microscopy (TEM) and a three dimensional atom probe (3DAP). The γ-Fe,Ni FCC crystals, 25 nm in size, were found in the amorphous alloy annealed at temperatures ranging 360–400 °C for 1 h. TEM demonstrates that the nanocrystals growth stops as the temperature rises. The formation of an amorphous layer enriched in boron at the border of γ-Fe,Ni nanocrystals responsible for the pinning of nanocrystals size was observed by 3DAP. The composition of an amorphous barrier by 3DAP was found to be Fe50Ni29B21. It was proposed that this composition reveals higher crystallization temperature, which is the reason of pinning nanocrystals growth.

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