抄録
In-situ observation of elastic deformation behaviors of Zr55Al10Ni5Cu30 bulk metallic glass under tensile stress was carried out using the high-energy X-ray scattering method. Two analytical procedures—the reciprocal-space method and direct-space method—were applied. The reciprocal-space method, used for the estimation of an apparent atomic spacing, can evaluate the strain in the range of several nanometers. We found that this method yields a large Young’s modulus (115 GPa) and a small Poisson’s ratio (0.32), as compared to the macroscopic values of 101 GPa and 0.38, respectively. Thus, the macroscopic deformation is larger than the microscopic deformation characterized by the X-ray scattering method. This feature indicates the possibility of inhomogeneous regions with weakly bonded structures existing locally in the glassy structure and acting as significant deformation sites in the elastic stage. The direct-space method suggests that the Zr-Zr nearest pair has a higher sensitivity to an applied stress than the Zr-Cu pair. Moreover, both the nearest pairs in the first shell (r<0.4 nm) exhibit a slight distortion, as compared with the deformation observed in the second or higher coordination shell (r>0.4 nm). We explain this deformability gap with the hypothesis that the free volume in the first coordination shell assists the glide of atoms. This results in a larger strain in the second or higher coordination shell than in the first shell.
