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

摘要

Al-Fe alloys containing 60, 65, 70, 75, 80, 83 and 85 at.% of Al were prepared by high-energy bail 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_(13)Fe)4 one in the case of the Al-20%Fe composition. Amorphous alloys crystallised upon heating yielding a mixture of Al_(13)Fe)4 intermetallic and Al.