Structural modifications in sub-Tg annealed CuZr-based metallic glass

Short term sub-glass transition annealing controls the structural reordering and nanocrystallization of CuZr based bulk metallic glasses (BMGs). Using this method, 5 times higher resistance against strain softening as confirmed by three-point bending tests is attained. Homogenously dispersed nanoparticles in sizes of 20-50 nm accounts for the remarkable shifts and peak formations on reciprocal space together with the diffraction spots observed on 2D diffraction pattern. Real-space pair distribution function analysis reveals noticeable changes in peak shapes and positions correlated with the changes in short-to medium-range ordering. The differences in the partial coordination numbers upon annealing mark the dominant Zr - Zr pair to diminish whereas the Cu Cu pair becomes prominent, hinting that Cu diffusion is mainly responsible for structural reordering and formation of new phases. The pursued study using hard X-ray synchrotron radiation reveals important aspects of structural changes preceding nanocrystallization, which in turn enhances the mechanical performance in BMGs.