Crystalline approximant of amorphous Fe-Si-B structures

We have examined the local atomic configurations of amorphous Fe-Si-B alloys by means of electron diffraction pair-distribution-function analysis and compared them with those of a metastable sigma phase formed during the crystallization process. We found a great structural similarity, not only at short range but also at medium range up to 1.0 nm, between amorphous Fe-Si-B and sigma phase structures. The results imply that the sigma phase structure can be regarded as a good crystalline approximant for the glass structures in this alloy system. The connections of coordination polyhedra in the sigma phase structure were also discussed.