Nanolayer formation during hydrodynamic instability under external stimuli

Experimental observations regarding the formation of strengthening surface nanostructures under various external stimuli (electroexplosive alloying, electron-beam treatment, thermomechanical strengthening of rolled strip by fast cooling, and intense mechanical treatment in long-term rail operation) are interpreted on the basis of consistent principles. The formation of nanostructures due to unstable equilibrium states in the surface layers (Kelvin–Helmholtz and Marangoni instabilities) is simulated. The corresponding dispersion equations are analyzed, and analytical formulas are derived for the decrement α as a function of the wavelength λ in the micro and nano ranges. The numerical values of the maxima in the α(λ) curve correspond to the experimental parameters of the nanostructures. A physical interpretation is offered.