Crystallization process and glass stability of an Fe₄₈Cr ₁₅ Mo₁₄C₁₅B₆Tm₂ bulk metallic glass

The crystallization process in an Fe₄₈Cr₁₅ Mo ₁₄ C₁₅ B₆ Tm₂ metallic glass has been investigated by means of nanobeam and selected area electron-diffraction techniques. We found that the first crystallization reaction proceeds through a complicated nanoscale process, that is, amorphous→χ-FeCrMo -like long-period structures→χ-FeCrMo→ M₂₃ C₆. A long-period structure began forming as an extended structure of medium range order; its periodicity gradually changed with the growing stage on annealing, and the structure finally changed into χ-FeCrMo. The common structural unit among these structures was found to be an atomic coordination polyhedron with a coordination number of 16. On the basis of the results, we discuss the phase stability of the Fe₄₈Cr₁₅Mo₁₄C ₁₅B₆Tm₂ metallic glass as well as its local atomic arrangements.