Nanocrystalline and amorphous Al–Fe alloys containing 60–85% of Al synthesised by mechanical alloying and phase transformations induced by heating of milling products

Abstract

Al–Fe alloys containing 60, 65, 70, 75, 80, 83 and 85 at.% of Al were prepared by high-energy ball milling. Thermal behaviour of the mechanically alloyed alloys was investigated using differential scanning calorimetry. The phase transformations and structural changes taking place in the materials during milling and during subsequent heating in a calorimeter were investigated by X-ray diffraction. For the alloys with 60% and 65% of Al, a supersaturated Fe(Al) solid solution was the milling product. For the Al–30%Fe composition it was a two-phase Al 5Fe 2 + Fe(Al) alloy, while for the Al–25%Fe and Al–20%Fe compositions an Al 5Fe 2 intermetallic, at least partially ordered, was produced. All these alloys were nanocrystalline. Amorphous alloys were obtained for the compositions with 83% and 85% of Al. Heating of the milling products in the calorimeter caused transformation of the solid solution into an ordered FeAl intermetallic, formation of Al 5Fe 2 intermetallic for the Al–35%Fe composition and transformation of Al 5Fe 2 intermetallic into Al 13Fe 4 one in the case of the Al–20%Fe composition. Amorphous alloys crystallised upon heating yielding a mixture of Al 13Fe 4 intermetallic and Al.