The nature of yielding and anelasticity in metals

Recent reports in the literature identified pre-yield stress-strain nonlinearity and hysteresis (anelasticity) as occurring in metals at virtually all stresses. These observations raise foundational questions about metal deformation. Does a critical stress exist below which dislocations are immobile? Is there a critical stress for which permanent deformation occurs? Is anelasticity distinct from elasticity and plasticity? To answer such...