  Prior to macroscopic yielding, most materials undergo a regime of plastic
activity that cannot be resolved in conventional bulk deformation experiments.
In this pre-yield, or micro-plastic regime, it is the initial three dimensional
defect network that is probed and the intermittently evolving microstructure
admits small increments in plastic strain. By reducing the sample size, this
intermittent activity becomes increasingly apparent and can be routinely
observed through small-scale mechanical testing. In some cases, the
intermittent activity was shown to exhibit aspects of scale-free behavior,
prompting a paradigm shift away from traditional microstructure-dependent unit
mechanisms that may be associated with a well defined length and stress scale.
In this article, we discuss and review connections between classical
micro-plasticity and intermittent flow across all length scales, with the aim
of highlighting the value of miniaturized testing as a means to unravel this
very early regime of bulk plasticity.
