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 atomic force microscopy and scanning white-light interferometry. We demonstrate that an initially smooth surface during deformation develops self-affine roughness over almost 4 orders of magnitude in scale. The Hurst exponent H of one-dimensional surface profiles initially decreases with increasing strain and then stabilizes at H approximately 0.75. We show that the profiles can be mathematically modeled 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.
Zaiser
Michael
M
Centre for Materials Science and Engineering, The University of Edinburgh, The King's Buildings, Sanderson Building, Edinburgh EH9 3JL, United Kingdom.
Grasset
Frederic Madani
FM
Koutsos
Vasileios
V
Aifantis
Elias C
EC