An interpretation of size-scale plasticity in geometrically confined systems.

摘要: The mesoscopic constitutive behavior of face-centered cubic metals as a function the system characteristic dimension recently has been investigated experimentally. Strong size effects have identified in both polycrystalline submicron thin films and single crystal micro pillars. effect is manifested an increase strength hardening rate dimensions are decreased. In this article, we provide mechanistic interpretation for observed behavior. By performing 3D discrete dislocation dynamics simulations grains representative microstructure associated dimensions, show that experimentally can be qualitatively described. these simulations, constant density sources per unit grain boundary area modeled by randomly distributed at boundaries. source length (strength) Gaussian distribution, which average standard deviation independent dimension. reveal two key concepts root plasticity effect. First, onset governed nucleation-controlled process (sources various length, i.e., strengths, our model). Second, controlled exhaustion, active only once result limited mobility arising from effects. model postulated here improves understanding why “smaller stronger” provides predictive capabilities should enhance reliable design devices applications such microelectronics micro/nano-electro-mechanical systems.