*Article* **From Statistical Correlations to Stochasticity and Size Effects in Sub-Micron Crystal Plasticity**

**Hengxu Song <sup>1</sup> and Stefanos Papanikolaou 1,2,\***


Received: 24 June 2019; Accepted: 25 July 2019; Published: 27 July 2019

**Abstract:** Metals in small volumes display a strong dependence on initial conditions, which translates into size effects and stochastic mechanical responses. In the context of crystal plasticity, this amounts to the role of pre-existing dislocation configurations that may emerge due to prior processing. Here, we study a minimal but realistic model of uniaxial compression of sub-micron finite volumes. We show how the statistical correlations of pre-existing dislocation configurations may influence the mechanical response in multi-slip crystal plasticity, in connection to the finite volume size and the initial dislocation density. In addition, spatial dislocation correlations display evidence that plasticity is strongly influenced by the formation of walls composed of bound dislocation dipoles.

**Keywords:** plasticity; representative volume element; dislocation structure; dislocation correlations; dislocation avalanches
