Amorphous and Nanostructured Al-Fe and Al-Ni Based Alloys

Al-based systems allow obtaining microstructures composed of different combination of several classes of phases: crystalline solid solutions, amorphous solid solutions, crystalline intermetallic compounds and quasicrystals. Many Al-Fe based systems are icosahedral phase former, but non icosahedral phase was reported in Al-Ni based systems. The strong hetero-atomic interaction in the liquid of Al-based alloys appears to have a big effect on the amorphous forming ability. In order to analyse the amorphous forming ability and the amorphous structure of Al-Fe and Al-Ni based alloys, series of samples were produced by melt spinning. The structure was characterized by means of X-ray diffraction, Mdssbauer spectroscopy and transmission electron microscopy. Clusters with medium range order in the Al-Fe based alloys were found and the icosahedral short range order in the amorphous structure is discussed. These alloys have a heterogeneous amorphous structure at nano-scale. The relationship among the different phases obtained by rapid solidification in the Al-Fe based systems is discussed considering the hetero-atomic interaction and the ability for clusters formation in the liquid.