Bulk nano-crystalline Fe-based alloys by annealing bulk glassy precursors

Bulk metallic glasses (BMGs) Fe–B–Y–Nb–Cu, 2 mm in diameter, were successfully annealed to become bulk nano-crystalline alloys (BNCAs) with α-Fe crystallite 11–13 nm in size. A ‘crystallization-and-stop’ model was proposed to explain this behavior. Following this model, alloy-design criteria were elucidated and testified successful on another Fe-based BMGs Fe–B–Si–Nb–Cu, 1 mm in diameter, with crystallite sizes 10–40 nm. It was concluded that BNCAs can be designed in general by the proposed criteria.