Controlling strength and toughness of multilayer films: A new multiscalar approach

Adams, David P.; Vill, M.; Jia, Ting; Bilello, J. C.; Yalisove, S. M.

doi:10.1063/1.354947

Cited by 35 publications

(8 citation statements)

References 24 publications

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“…A rough growth surface can lead to a decreased film density when voids form along columnar grain boundaries as a result of self-shadowing [96]. Deposition onto a severely roughened surface can further result in a distribution of reactant layer thicknesses rather than the single, intended value for each reactant [73].…”

Section: Properties Of As-deposited Multilayers (Prior To Ignition)mentioning

confidence: 98%

Reactive multilayers fabricated by vapor deposition: A critical review

2015

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a b s t r a c t a r t i c l e i n f o Available online xxxxReactive multilayer thin films are a class of energetic materials that continue to attract attention for use in joining applications and as igniters. Generally composed of two reactants, these heterogeneous solids can be stimulated by an external source to promptly release stored chemical energy in a sudden emission of light and heat. In this critical review article, results from recent investigations of these materials are discussed. Discussion begins with a brief description of the vapor deposition techniques that provide accurate control of layer thickness and film composition. More than 50 reactive film compositions have been reported to date, with most multilayers fabricated by magnetron sputter deposition or electron-beam evaporation. In subsequent sections, we review how multilayer ignition threshold, reaction rate, and total heat are tailored via thin film design. For example, planar multilayers with nanometer-scale periodicity exhibit rapid, self-sustained reactions with wavefront velocities up to 100 m/s. Numeric and analytical models have elucidated many of the fundamental processes that underlie propagating exothermic reactions while demonstrating how reaction rates vary with multilayer design. Recent, time-resolved diffraction and imaging studies have further revealed the phase transformations and the wavefront dynamics associated with propagating chemical reactions. Many reactive multilayers (e.g., Co/Al) form product phases that are consistent with published equilibrium phase diagrams, yet a few systems, such as Pt/Al, develop metastable products. The final section highlights current and emerging applications of reactive multilayers. Examples include reactive Ni(V)/Al and Pd/Al multilayers which have been developed for localized soldering of heat-sensitive components.

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Section: Properties Of As-deposited Multilayers (Prior To Ignition)mentioning

confidence: 98%

Reactive multilayers fabricated by vapor deposition: A critical review

2015

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“…Since the 1980s, fundamental research has been carried out on these LMCs and it was shown that the internal material interfaces play an important role on the monotonic and cyclic mechanical properties. The monotonic strength of LMCs is significantly higher than that of the mono‐material reference sheets, if the layer thickness is in the sub‐micron range . Under cyclic loading, a pronounced crack bifurcation at the material interface is the key to prolonged fatigue lives .…”

Section: Introductionmentioning

confidence: 99%

High Lightweight Potential of Ultrafine‐Grained Aluminum/Steel Laminated Metal Composites Produced by Accumulative Roll Bonding

et al. 2018

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The focus of this paper is the designing of ultrafine-grained aluminum/steel laminated metal composites for innovative lightweight materials concepts used for cyclic loading. These ultrafine-grained composites are produced by the accumulative roll bonding process. Three different aluminum/steel composites are studied, where the position of the steel layers is varied, to investigate the influence of the layer architecture. The mechanical properties are measured in monotonic and cyclic three-point bending tests. The influence of the meso-and microstructure are intensively studied by scanning electron microscope observations. Furthermore, the internal stresses during elastic straining are calculated by a finite element simulation. In the composites, both monotonic and cyclic mechanical properties are strongly increased and are clearly higher as expected by a linear rule of mixtures of the constituent materials. This increase is particularly high for the fatigue properties resulting in a strongly enhanced specific fatigue limit of the composites.

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“…Sputter-deposited metallic thin films are used heavily in the semiconductor [1,2], magnetic recording media [3], and wear-resistant coatings industries [4]. For this reason, any study showing how to better control the microstructural evolution in these layers is of interest.…”

Section: Introductionmentioning

confidence: 99%

Deposition Kinetics and Microstructural Evolution in Sputtered TA Films: a Real-Time/In-Situ Study

1999

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Ta films were grown using sputter gas (Ar) pressures ranging from 1.7 to 20 mTorr. This produced growth environments where incoming adatom kinetic energies ranged from over 100 eV to less than I eV. Film development was monitored in-situ using a x-ray diffraction set-up that allowed complete diffraction patterns to be rapidly collected without interrupting the growth process. Traditional x-ray diffraction methods, transmission electron microscopy (TEM), and transmission electron diffraction (TED) were used to examine film microstructure after growth. It was found that lower Ar pressures, which allow higher adatom kinetic energies, produced films that displayed significant grain growth, texturing, and a smooth surface morphology. Those films grown at increasingly higher Ar pressures displayed smaller grain sizes, less texturing, and increasingly porous microstructures. To further explore this effect, the Ar pressure was varied during deposition for several films. The in-situ probe allowed the effects of each pressure increment to be analyzed and compared with previous x-ray and microscopy results. It was found that the microstructure of any particular film layer depended more on the deposition conditions during its formation rather than the structure or crystallography of previous layers.

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Controlling strength and toughness of multilayer films: A new multiscalar approach

Cited by 35 publications

References 24 publications

Reactive multilayers fabricated by vapor deposition: A critical review

Reactive multilayers fabricated by vapor deposition: A critical review

High Lightweight Potential of Ultrafine‐Grained Aluminum/Steel Laminated Metal Composites Produced by Accumulative Roll Bonding

Deposition Kinetics and Microstructural Evolution in Sputtered TA Films: a Real-Time/In-Situ Study

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