Configurational dependence of elastic modulus of metallic glass

YQ Cheng and E Ma, PHYSICAL REVIEW B, 80, 064104 (2009).

DOI: 10.1103/PhysRevB.80.064104

The shear modulus (G) of metallic glass depends sensitively on the internal amorphous structure, in addition to being lower than that of the crystal counterpart. To uncover the origin of this behavior, we have performed extensive atomistic simulations of model alloys with varying internal structures, but all at the same Cu50Zr50 composition. We demonstrate that G is sensitively dependent on the correlations of the atomic shear stresses. A systematic comparison of these alloys reveals obvious differences in the correlations of the atomic shear stresses in the medium-to-long range, at length scales beyond similar to 1.2 nm. This reflects a major difference in these different structural configurations, in terms of the transverse coupling between the local atomic clusters and their surrounding confinement. This coupling is strongly influenced by the degree of structural ordering, leading to the obvious configurational dependence of G. The bulk modulus and the underlying correlations of the atomic pressure, in contrast, are insensitive to the configurational variations.

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