Induced elastic anisotropy in a bulk metallic glass

Full evaluation of the elasticity tensor of a bulk metallic glass (Pd40Cu30Ni10P20) shows anisotropy induced by creep under uniaxial compression changing sign with increasing strain. Anisotropy due to anelastic strain is erased by zero stress annealing. At higher strain anisotropy of opposite sign suggests structural alignment by plastic flow. Induced anisotropy is most evident in the Poisson ratio, may relate to other properties, including the strength and toughness of metallic glasses, and may lead to misinterpretation of annealing effects.

► First determination of the full elasticity tensor of a bulk metallic glass.
► First observation of anisotropy in any metallic glass induced after casting.
► Observation that elastic anisotropy can be induced by creep.
► Discovery that the induced anisotropy changes sign as creep continues.
► Implication that there is an anisotropy associated with plastic flow, and not just with anelastic strain as previously supposed.