Electronic structure and FIM imaging mechanism of Fe−Al intermetallic compounds

Abstract

The electronic structure and some one-electron properties of binary intermetallic compounds Fe3Al (the F1∶Al4 model cluster) and FeAl (the Fe7Al8 and Fe4Al4 model clusters) are investigated by the SCF-Xα-SW method. The results show that the binding tendency between an Fe atom and the Fe3Al cluster is a little weaker than that between an Al atom and the Fe3Al cluster, which is in contrast to the case in FeAl. And charge is transferred from Al atoms to Fe atoms in both systems. Thus it is concluded that Al atoms contribute to the FIM image of Fe3Al whatever the imaging mechanism, selective evaporation or selective ionization is, which is in good agreement with our FIM experimental results. For FeAl, no definite experimental evidence regarding FIM imaging atom species is available so far. But our calculated result that Al atoms will be evaporated preferentially leads to the prediction that Fe atoms will be imaged in FIM micrographs.