SeRC-MD seminar: Shock-induced plasticity and phase transitions in metals: new insights from molecular dynamics simulations

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The talk will be given by Prof. Ivan Oleynik from University of South Florida (oleynik at usf.edu).

Time: 21st December 2012, 13:15
Place: FA31, AlbaNova Univ Center

Abstract:
I.I. Oleynik, Department of Physics, University of South Florida, Tampa, FL, USA

Shock waves propagate through solids at supersonic speeds and, if powerful enough,
can induce irreversible plastic deformations and phase transitions. Although the
shock-induced phenomena in materials have been the focus of intense experimental
and theoretical investigations, the atomic scale mechanisms coupling the shock-induced materials transformations to initial elastic compression remain poorly understood. In this talk I will discuss several new phenomena that were discovered in large-scale molecular dynamics simulations of shock waves in metals. By decoupling time and length scales using novel moving window molecular dynamics technique, a new regime of shock-wave propagation was uncovered characterized by a two-zone elastic-plastic shock wave structure consisting of a leading elastic front followed by a plastic front, both moving with the same average speed and having a fixed net thickness that can extend to microns. At higher shock intensities, moving window molecular dynamics was used to follow the evolution of orientation-dependent metastable states during shock-induced solid-liquid phase transitions in crystalline aluminum including ‘‘cold melting’’ followed by recrystallization in [110]- and [111]-oriented shock waves and crystal overheating followed by melting in [100] shock waves