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Title: Effect of varying bilayer spacing distribution on reaction heat and velocity in reactive Al/Ni multilayers

Abstract

Self-propagating reactions in Al/Ni nanostructured multilayer foils are examined both experimentally and computationally to determine the impact of variations in reactant spacing on reaction properties. Heats of reaction and reaction velocities have been characterized as a function of average bilayer spacing for sputter-deposited, single-bilayer foils (having a uniform bilayer spacing) and for dual-bilayer foils (having two different bilayer spacings that are labeled thick and thin). In the latter case, the spatial distribution of the thick and thin bilayers is found to have a significant effect on reaction velocity, with coarse distributions leading to much higher reaction velocities than fine distributions. Numerical simulations of reaction velocity match experimental data well for most spatial distributions, with the exception of very coarse distributions or distributions containing very small bilayer spacings. A simple model based on thermal diffusivities and reaction velocities is proposed to predict when the spatial distribution of thick and thin bilayers becomes coarse enough to affect reaction velocity. This combination of experiment and simulation will allow for more effective design and prediction of reaction velocities in both sputter-deposited and mechanically processed reactive materials with variable reactant spacings.

Authors:
; ; ;  [1];  [2];  [3]
  1. Department of Materials Science and Engineering, Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218 (United States)
  2. Department of Mechanical Engineering, United States Naval Academy, 121 Blake Rd., MS 11C, Annapolis, Maryland 21402 (United States)
  3. Department of Mechanical Engineering, Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218 (United States)
Publication Date:
OSTI Identifier:
21356103
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 105; Journal Issue: 8; Other Information: DOI: 10.1063/1.3087490; (c) 2009 American Institute of Physics; Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; ALUMINIUM; COMPUTERIZED SIMULATION; DEPOSITION; FOILS; LAYERS; NANOSTRUCTURES; NICKEL; NUMERICAL ANALYSIS; REACTION HEAT; REACTION KINETICS; SPATIAL DISTRIBUTION; SPUTTERING; THERMAL DIFFUSIVITY; DISTRIBUTION; ELEMENTS; ENTHALPY; KINETICS; MATHEMATICS; METALS; PHYSICAL PROPERTIES; SIMULATION; THERMODYNAMIC PROPERTIES; TRANSITION ELEMENTS

Citation Formats

Knepper, Robert, Fritz, Greg, Fisher, Kaitlynn, Weihs, Timothy P., Snyder, Murray R., and Knio, Omar M. Effect of varying bilayer spacing distribution on reaction heat and velocity in reactive Al/Ni multilayers. United States: N. p., 2009. Web. doi:10.1063/1.3087490.
Knepper, Robert, Fritz, Greg, Fisher, Kaitlynn, Weihs, Timothy P., Snyder, Murray R., & Knio, Omar M. Effect of varying bilayer spacing distribution on reaction heat and velocity in reactive Al/Ni multilayers. United States. doi:10.1063/1.3087490.
Knepper, Robert, Fritz, Greg, Fisher, Kaitlynn, Weihs, Timothy P., Snyder, Murray R., and Knio, Omar M. Wed . "Effect of varying bilayer spacing distribution on reaction heat and velocity in reactive Al/Ni multilayers". United States. doi:10.1063/1.3087490.
@article{osti_21356103,
title = {Effect of varying bilayer spacing distribution on reaction heat and velocity in reactive Al/Ni multilayers},
author = {Knepper, Robert and Fritz, Greg and Fisher, Kaitlynn and Weihs, Timothy P. and Snyder, Murray R. and Knio, Omar M.},
abstractNote = {Self-propagating reactions in Al/Ni nanostructured multilayer foils are examined both experimentally and computationally to determine the impact of variations in reactant spacing on reaction properties. Heats of reaction and reaction velocities have been characterized as a function of average bilayer spacing for sputter-deposited, single-bilayer foils (having a uniform bilayer spacing) and for dual-bilayer foils (having two different bilayer spacings that are labeled thick and thin). In the latter case, the spatial distribution of the thick and thin bilayers is found to have a significant effect on reaction velocity, with coarse distributions leading to much higher reaction velocities than fine distributions. Numerical simulations of reaction velocity match experimental data well for most spatial distributions, with the exception of very coarse distributions or distributions containing very small bilayer spacings. A simple model based on thermal diffusivities and reaction velocities is proposed to predict when the spatial distribution of thick and thin bilayers becomes coarse enough to affect reaction velocity. This combination of experiment and simulation will allow for more effective design and prediction of reaction velocities in both sputter-deposited and mechanically processed reactive materials with variable reactant spacings.},
doi = {10.1063/1.3087490},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 8,
volume = 105,
place = {United States},
year = {2009},
month = {4}
}