Atomic structure of FeAl{001}

The atomic structure of a clean {001} surface of the ordered binary alloy FeAl with 46 at% Al (lattice parameter 2.904 Å) has been determined by low-energy electron diffraction analysis. The bulk structure is of the CsCl-type. The top surface plane is shown to be an Al layer, with an Fe plane for the second layer. The first interlayer spacing (between Al and Fe) is found to be contracted by 14.6%, while the second interlayer spacing (between Fe and Al) is found to be expanded by 4%. A sputter-cleaned but not annealed surface of this alloy is found to have ordered regions of predominantly bcc Fe{001}. © 1993.