Revealing Transient Phase Evolution in Reactive Multi-layer Foils using Dynamic TEM

LaGrange, T; Reed, BW; Campbell, G H; Lomov, I.; Austin, Ryan; Gash, Alexander E.; Kim, J.S.; Adams, David P.

doi:10.1017/s1431927612004084

Cited by 1 publication

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similarly, a smooth wavefront is observed in Ti/2B when imaged with nanometer spatial resolution using dynamic TEM, as in Fig. 14 [151]. In this case, a narrow, uniform reaction zone (~1 μm in width) is present along the boundary between reacted TiB 2 and the unreacted Ti/2B multilayer.…”

Section: Characteristics Of Steady Reaction Frontsmentioning

confidence: 60%

“…In applications that involve multilayer heat sources, such as joining or power sources, multilayers may exceed 100 μm total thickness. In contrast, thin multilayers,~100-200 nm, are typically used in dynamic TEM experiments [3,140,151]. It is noted that the minimum total thickness for selfpropagating reactions has not been determined rigorously for any materials system.…”

Section: Planar Multilayers Exhibiting Self-propagating Reactionsmentioning

confidence: 99%

“…In this case, a narrow, uniform reaction zone (~1 μm in width) is present along the boundary between reacted TiB 2 and the unreacted Ti/2B multilayer. Behind this boundary, a granular structure is formed upon resolidification [151].…”

Section: Characteristics Of Steady Reaction Frontsmentioning

confidence: 99%

“…Temporal resolution as small as~55 μs was reported for this approach [142,168]. DTEM is a related pumpprobe method that provides images and diffraction information with 15 ns temporal and 10 nm spatial resolution [3,140,151]. Evaluation requires a much thinner specimen (b200 nm in total thickness), which is electron transparent.…”

Section: Phase Evolution During Steady Propagating Reactionsmentioning

confidence: 99%

“…DTEM has provided additional details regarding the phase transformations occurring in Ni-Al [3,140] and Ti-B [151] multilayers. The phases formed in Ni-Al multilayers have been studied for three different compositions, 2:3, 1:1 and 3:2 Ni:Al atomic ratios.…”

Section: Phase Evolution During Steady Propagating Reactionsmentioning

confidence: 99%

See 4 more Smart Citations

Reactive multilayers fabricated by vapor deposition: A critical review

2015

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Characteristics Of Steady Reaction Frontsmentioning

confidence: 60%

Section: Planar Multilayers Exhibiting Self-propagating Reactionsmentioning

confidence: 99%

Section: Characteristics Of Steady Reaction Frontsmentioning

confidence: 99%