Homogeneous deformation of metallic glass at room temperature reveals large dilatation

Room-temperature uniaxial compression of Zr46.75Ti8.25Cu7.5Ni10Be27.5 bulk metallic glass at 80% of the yield stress leads to homogeneous viscous flow. The flow in this apparently elastic regime reveals large increases in volume associated with local shearing events in the glass. The extent of this dilatation is masked in more usual tests by significant relaxation of the glass structure during and after shear. The dilatation in deformed metallic glasses can no longer be attributed only to free-volume generation at shear bands.

Research highlights
► We study compressive loading of a metallic glass below the yield stress.
► The directly measured density decrease verifies earlier indirect inferences.
► There is a dilatation of roughly one atomic volume per atom involved in shear.
► Volume changes cannot now be attributed only to shear bands.
► The relative changes of shear and bulk moduli are not as expected.