A simplified computational model of the oxidation of Zr/Al multilayers

Vohra, Manav; Weihs, Timothy P.; Knio, Omar M.

doi:10.1016/j.combustflame.2014.07.010

Cited by 13 publications

(3 citation statements)

References 41 publications

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“…A simplified model was subsequently developed to characterize the oxidation behavior in the equimolar Zr-Al system. 22 However, despite the availability of a body of experimental evidence concerning anaerobic formation reactions in the Zr-Al system (see, e.g., Refs. 23 and references therein), a computational model that can describe the evolution of anaerobic formation reactions in the Zr-Al system is not available.…”

Section: Introductionmentioning

confidence: 99%

Development of a reduced model of formation reactions in Zr-Al nanolaminates

Vohra

Winokur

Overdeep

et al. 2014

Journal of Applied Physics

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A computational model of anaerobic reactions in metallic multilayered systems with an equimolar composition of zirconium and aluminum is developed. The reduced reaction formalism of M. Salloum and O. M. Knio, Combust. Flame 157(2): 288–295 (2010) is adopted. Attention is focused on quantifying intermixing rates based on experimental measurements of uniform ignition as well as measurements of self-propagating front velocities. Estimates of atomic diffusivity are first obtained based on a regression analysis. A more elaborate Bayesian inference formalism is then applied in order to assess the impact of uncertainties in the measurements, potential discrepancies between predictions and observations, as well as the sensitivity of predictions to inferred parameters. Intermixing rates are correlated in terms of a composite Arrhenius law, which exhibits a discontinuity around the Al melting temperature. Analysis of the predictions indicates that Arrhenius parameters inferred for the low-temperature branch lie within a tight range, whereas the parameters of the high-temperature branch are characterized by higher uncertainty. The latter is affected by scatter in the experimental measurements, and the limited range of bilayers where observations are available. For both branches, the predictions exhibit higher sensitivity to the activation energy than the pre-exponent, whose posteriors are highly correlated.

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Section: Introductionmentioning

confidence: 99%

Development of a reduced model of formation reactions in Zr-Al nanolaminates

Vohra

Winokur

Overdeep

et al. 2014

Journal of Applied Physics

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“…Current research explores ways to tailor the degree of surface oxidation because it is of interest for various applications. Whereas latest studies demonstrated that chemistry or stoichiometry variation affects oxidation 40 41 , we will now show that Λ variations (while keeping chemistry constant) can also be utilized to control oxidation. Intriguingly when increasing Λ from 22 nm to 88 nm the double-structured oxidation scale decreases to a negligible amount, Fig.…”

Section: Resultsmentioning

confidence: 71%

Ru/Al Multilayers Integrate Maximum Energy Density and Ductility for Reactive Materials

Woll

Bergamaschi

Avchachov

et al. 2016

Sci Rep

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Established and already commercialized energetic materials, such as those based on Ni/Al for joining, lack the adequate combination of high energy density and ductile reaction products. To join components, this combination is required for mechanically reliable bonds. In addition to the improvement of existing technologies, expansion into new fields of application can also be anticipated which triggers the search for improved materials. Here, we present a comprehensive characterization of the key parameters that enables us to classify the Ru/Al system as new reactive material among other energetic systems. We finally found that Ru/Al exhibits the unusual integration of high energy density and ductility. For example, we measured reaction front velocities up to 10.9 (±0.33) ms−1 and peak reaction temperatures of about 2000 °C indicating the elevated energy density. To our knowledge, such high temperatures have never been reported in experiments for metallic multilayers. In situ experiments show the synthesis of a single-phase B2-RuAl microstructure ensuring improved ductility. Molecular dynamics simulations corroborate the transformation behavior to RuAl. This study fundamentally characterizes a Ru/Al system and demonstrates its enhanced properties fulfilling the identification requirements of a novel nanoscaled energetic material.

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“…The multilayers support self-propagating reactions that travel along the direction of the layers at speeds ranging from several centimeters per second to tens of meters per second [2][3][4][5]. These special properties make them attractive for a wide range of applications, including joining processes such as welding, soldering and brazing [6][7][8][9][10][11][12][13], and ignition of secondary reactions and defeat of biocidal agents [14][15][16][17][18][19][20][21]. Advances in fabrication techniques [2,19,[22][23][24][25][26][27] enabling control of the microstructure of metallic multilayers at the atomistic levels, as well as simultaneous discovery of novel applications, have motivated a sustained development of reaction models for more than three decades.…”

Section: Introductionmentioning

confidence: 99%

Design analysis for optimal calibration of diffusivity in reactive multilayers

Vohra

Huan

Weihs

et al. 2017

Combustion Theory and Modelling

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Calibration of the uncertain Arrhenius diffusion parameters for quantifying mixing rates in Zr-Al nanolaminate foils was performed in a Bayesian setting [1]. The parameters were inferred in a low temperature regime characterized by homogeneous ignition and a high temperature regime characterized by self-propagating reactions in the multilayers. In this work, we extend the analysis to find optimal experimental designs that would provide the best data for inference. We employ a rigorous framework that quantifies the expected information gain in an experiment, and find the optimal design conditions using numerical techniques of Monte Carlo, sparse quadrature, and polynomial chaos surrogates. For the low temperature regime, we find the optimal foil heating rate and pulse duration, and confirm through simulation that the optimal design indeed leads to sharper posterior distributions of the diffusion parameters. For the high temperature regime, we demonstrate potential for increase in the expected information gain of the posteriors by increasing sample size and reducing uncertainty in measurements. Moreover, posterior marginals are also produced to verify favorable experimental scenarios for this regime. † Corresponding Author

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A simplified computational model of the oxidation of Zr/Al multilayers

Cited by 13 publications

References 41 publications

Development of a reduced model of formation reactions in Zr-Al nanolaminates

Development of a reduced model of formation reactions in Zr-Al nanolaminates

Ru/Al Multilayers Integrate Maximum Energy Density and Ductility for Reactive Materials

Design analysis for optimal calibration of diffusivity in reactive multilayers

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