Crystallization process and glass stability of an Fe48Cr15Mo14C15B6Tm2 bulk metallic glass

The crystallization process in an Fe48Cr15Mo14C15B6Tm2 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 ->chi-FeCrMo-like long-period structures ->chi-FeCrMo -> M23C6. 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 chi-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 Fe48Cr15Mo14C15B6Tm2 metallic glass as well as its local atomic arrangements.