1, Sandia National Laboratories, Albuquerque, New Mexico, United States
The propagation of sputter deposited Co/Al nanolaminates is known to have a bilayer thickness dependent instability. The specific 2D instability observed involves the transverse propagation of a band in front of a stalled front commonly referred to as a “spin band.” Previous laser ignition studies have revealed that preheating to the point of pre-reaction removes enough stored chemical energy to slow propagation. Here, a single step diffusion limited reaction model is implemented into a time dependent heat spreading model to calculate the magnitude of pre-reaction ahead of a propagating front. To determine the amount of stored chemical energy lost as a function of pre-reaction thickness, films with product phase diffusion barriers were grown and characterized. This pre-reaction model is combined with an analytical calculation of propagation velocity, which allows for a prediction of quench length. The energy-depletion based model for spin band width is then tested on normally stable bilayer designs where instabilities have been induced through the addition of diluent product phase layers within the reactant layers.
This work was supported by the Sandia National Laboratory Directed Research and Development
(LDRD) program. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under Contract No. DE-NA0003525. This work describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S.
Department of Energy or the U.S. Government.