Aging in the shear-transformation-zone theory of plastic deformation

Publication Type
Journal Article
Year of Publication
Rottler, Jörg
Maass, Philipp
Name of Publication
Physical Review E

Aging phenomena in the plastic response of amorphous solids are studied within the theory of shear transformation zones {(STZs)}, which describes the kinetic rearrangement of localized defects in response to external stress. To account for the slow, nonequilibrium dynamics after a quench below the glass transition temperature, two possible models are considered. In the first model, transition rates between the internal states of {STZs} decrease with time, while in the second model aging occurs due to the relaxation of an effective temperature that determines the number density of {STZs} and other out-of-equilibium degrees of freedom. It is shown that for reasonable choices of parameters, both models capture qualitatively typical aging features seen in computer simulations and experiments: (i) compliance curves measured for different waiting times tw after the quench can be superimposed, when the observation times are rescaled with relaxation times ∝twμ, 0{\textless}μ⩽1, and (ii) stress-strain curves show a stationary plateau stress independent of tw and a peak stress that increases logarithmically with both tw and the strain rate. Trends of the aging behavior with the quench temperature are also discussed.