Thermal stability of Al-Ni-Fe-La aluminum amorphous alloys

The thermal stability of aluminum amorphous alloys with various contents of nickel, iron, and lanthanum is studied by differential scanning calorimetry, X-ray diffraction, and electron-microscopic analysis in the initial state and after heat and deformation treatment. The alloys are found to crystallize in two stages. The alloy with the maximum iron content (Al85Ni7Fe4La4) is shown to have the maximum thermal stability. Preliminary annealing at temperatures below the temperature of the onset of crystallization weakly affects this temperature. Preliminary severe plastic deformation increases the thermal stability of the alloys, which is caused by the existence of the first stage of crystallization during deformation. The structural aspects affecting the thermal stability of the alloys are considered.