Computer simulation and experimental study of elastic properties of amorphous Cu-Zr alloys

摘要

Molecular-dynamics simulations were performed to determine the elastic constants of Cu_xZr_(100-x)(33.3 ≤ x ≤ 64.5) metallic glasses at room temperature. The accuracy of the interatomic potentials used to obtain the model glass structures was tested by comparing to the total structure factors obtained from high-energy synchrotron x-ray diffraction and, more importantly, to acoustic velocities measured from melt spun ribbons. Both the simulated and measured acoustic velocities increased at comparable rates with increasing Cu concentration, but the former underestimated the latter by about 10%. Young's moduli of the simulated models were determined by combining the ultrasonic data with densities that were obtained from simulations. In addition, the compositional dependence of Poisson's ratio, shear modulus, and bulk modulus for this series of simulated metallic glasses was determined. Examination of partial-pair correlations deduced from simulated glass structures shows a correlation between higher bulk moduli in Cu-rich compositions and concomitant changes in Zr-Zr nearest neighbors, which exhibit a stronger sensitivity to an imposed hydrostatic stress than do Cu-Cu or Cu-Zr nearest-neighbor distances.