The Creep Deformation and Structural Dynamics of Zr _47.5Cu _47.5Al ₅ Metallic Glass Upon DCT Treatment

Abstract

Thermal cycling on the time-dependent plastic deformation and structure dynamic of a Zr 47.5 Cu 47.5 Al 5 metallic glass (MG) for the as-cast and the relaxed states is investigated. The result shows that rejuvenation or improvement of creep deformation is ascribed to the activation of total defects-controlled STZ (DC-STZ) volumes. During deep cryogenic treatment (DCT), the irreversible local atomic rearrangements bring more inherent defects, which provides enough activate sites for shear transformation zone (STZ) and further improves the activated of DC-STZ volumes. Meanwhile, we find the higher E β can impede defects formation and reduce the total activated DC-STZs volumes, which may be responsible for the different responds on the creep deformation and structural dynamic for both initial states of Zr 47.5 Cu 47.5 Al 5 MG. Moreover, neutron total scattering reveals that the thermal cycling can induce the change of medium-range order (MRO) due to non-affine thermal stress, but this process is irrelevant with the initial states of the samples.

Keywords: Metallic glasses, rejuvenation, creep deformation, medium-range order, neutron total scattering