CALCULATION OF SOME METALLIC-GLASS PROPERTIES, BASED ON THE USE OF A GAUSSIAN DISTRIBUTION FOR THE NEAREST-NEIGHBOR DISTANCE .3. ELASTIC-CONSTANTS

Abstract

Simple expressions for the shear modulus G and the bulk modulus B for an amorphous metal are derived. The derivation was accomplished by using a Gaussian distribution for the nearest-neighbour distance and a two-particle interatomic potential. It is shown that the difference between G or B and their crystalline counterparts is proportional to the square of the dispersion sigma-x on the Gaussian distribution; further, the difference is proportional to a function of the potential parameters. It is demonstrated that the anharmonic contribution to the potential determines nearly entirely the different elastic behaviour of amorphous metals in comparison with crystalline material. Further, the change DELTA-G in G during irreversible relaxation was calculated as a function of the change DELTA-sigma-x, and it was related to measurable quantities such as the changes in the mean atomic volume, in the mean energy per atom and in the height of the first maximum of the pair correlation function. The increase in G during annealing is explained in a natural way. The validity of most of the derived equations is confirmed semiquantitatively by experiment.