Improvement the plasticity of Fe-based bulk metallic glass via low temperature annealing

Generally, annealing below the glass transition temperature causes embrittlement of the bulk metallic glasses (BMGs). Here we found the plasticity of Fe₇₅Mo₅P₁₃C₇ BMG can be improved by annealing at low temperature. The improvement of plasticity is attributed to bits of nano-crystallization during the annealing and the free volume which has not been annihilated. The correlation of plasticity with micro-structure, relaxation and free volume characteristic varies in Fe₇₅Mo₅P₁₃C₇ BMG with its annealed state under different temperatures. It is demonstrated that the ratio of relaxation enthalpy decreases rapidly with the annealed temperature, and the ratio of crystallization increases slowly with the annealed temperature. The plasticity will be largest when the ratio of nanocrystals is equivalent to the free volume.