Vasileios Koutsos | Searcharxiv

arXiv2007

Scale-free statistics of plasticity-induced surface steps on KCl single crystals

Experimental investigations of plastic flow have demonstrated temporal intermittency as deformation proceeds in a series of intermittent bursts with scale-free size distribution. In the present investigation, a corresponding spatial intermittency is demonstrated for plastic flow of KCl single crystals. Deformation bursts lead to large surface steps with a height distribution that is consistent with the distribution of strain increments in deformation of micro-columns, and the energy distribution of acoustic emission bursts observed in deformation of macroscopic single crystal samples of a wide class of materials.

cond-mat.mtrl-sci↗

arXiv2004

Self-affine surface morphology of plastically deformed metals

We analyze the surface morphology of metals after plastic deformation over a range of scales from 10 nm to 2 mm, using a combination of atomic force microscopy and scanning white-light interferometry. We demonstrate that an initially smooth surface during deformation develops self-affine roughness over almost four orders of magnitude in scale. The Hurst exponent $H$ of one-dimensional surface profiles is initially found to decrease with increasing strain and then stabilizes at $H \approx 0.75$. By analyzing their statistical properties we show that the one-dimensional surface profiles can be mathematically modelled as graphs of a fractional Brownian motion. Our findings can be understood in terms of a fractal distribution of plastic strain within the deformed samples.

cond-mat.stat-mech↗