Effects of replacing Ni by Co on the crystallization behaviors of Al–Ni–La amorphous alloys

Effects of replacing Ni by Co on the crystallization behaviors of three Al–Ni–La amorphous alloys, i.e. Al85Ni9La6, Al86Ni9La5 and Al87Ni8La5 were investigated by X-ray diffraction and differential scanning calorimeter. The results show that the glass-forming ability decreases when Ni is replaced by excessive Co. Meanwhile replacing Ni by Co improves the thermal stability, enlarges the supercooled liquid region ΔTx and promotes the precipitation of the metastable phase(s) as the primary phase. The apparent activation energy Ea1 of the first reaction changes complicatedly during the replacement and is strongly dependent on the type of the primary phase, i.e. diffusion of atoms.