Impact sensitivity of intermetallic nanocomposites: A study on compositional and bulk density

Hunt, Emily M.; Pantoya, Michelle L.

doi:10.1016/j.intermet.2010.04.015

Cited by 36 publications

(19 citation statements)

References 15 publications

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“…1,7 However, nanoscale reactive composites are significantly more sensitive to impact and thermal ignition and have faster reaction rates than mixtures using micron size powders due to higher surface areas and smaller diffusion distances. 2,8,9 It has also been observed that higher bulk densities can lower impact ignition thresholds in nano mixtures. 2 In addition, material properties such as ductility and yield strength will also play a large role.…”

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confidence: 98%

“…2,8,9 It has also been observed that higher bulk densities can lower impact ignition thresholds in nano mixtures. 2 In addition, material properties such as ductility and yield strength will also play a large role. For example, when the a)…”

mentioning

confidence: 98%

“…Their potential use as structural energetic materials, as enhanced blast materials and for the synthesis of novel metastable non-equilibrium materials has driven research focused on their mechanical impact behavior. [1][2][3] Numerous experimental and theoretical studies have been published on impact behavior and shock compression of metal-based reactive powder mixtures with metals such as Al, Ni, Si, Ti, W, Nb, and more. [1][2][3][4][5] Yet the fundamental mechanisms that govern the initiation and front propagation are not well understood.…”

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confidence: 99%

“…[1][2][3] Numerous experimental and theoretical studies have been published on impact behavior and shock compression of metal-based reactive powder mixtures with metals such as Al, Ni, Si, Ti, W, Nb, and more. [1][2][3][4][5] Yet the fundamental mechanisms that govern the initiation and front propagation are not well understood. For example, their energy release characteristics depend on the mode of initiation, and reaction propagation, in a currently unpredictable way.…”

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confidence: 99%

“…It was theorized that the lower ignition threshold of W/Al is due to the harder material (W) slicing through the more ductile material (Al) upon impact creating fresh interfaces and igniting the sample. 2 Therefore, for the W/Al reactive composite, the energy needed to initiate reaction is acquired through both mechanical and thermal means; whereas for the Ni/Al reactive composite, the energy needed to initiate reaction is acquired mainly through thermal build up during the impact.…”

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confidence: 99%

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The role of microstructure refinement on the impact ignition and combustion behavior of mechanically activated Ni/Al reactive composites

Mason

Groven

Son

2013

Journal of Applied Physics

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Metal-based reactive composites have great potential as energetic materials due to their high energy densities and potential uses as structural energetic materials and enhanced blast materials however these materials can be difficult to ignite with typical particle size ranges. Recent work has shown that mechanical activation of reactive powders increases their ignition sensitivity, yet it is not fully understood how the role of microstructure refinement due to the duration of mechanical activation will influence the impact ignition and combustion behavior of these materials. In this work, impact ignition and combustion behavior of compacted mechanically activated Ni/Al reactive powder were studied using a modified Asay shear impact experiment where properties such as the impact ignition threshold, ignition delay time, and combustion velocity were identified as a function of milling time. It was found that the mechanical impact ignition threshold decreases from an impact energy of greater than 500 J to an impact energy of $50 J as the dry milling time increases. The largest jump in sensitivity was between the dry milling times of 25% of critical reaction milling time (t cr ) (4.25 min) and 50% t cr (8.5 min) corresponding to the time at which nanolaminate structures begin to form during the mechanical activation process. Differential scanning calorimetry analysis indicates that this jump in the sensitivity to thermal and mechanical impact is dictated by the formation of nanolaminate structures, which reduce the temperature needed to begin the dissolution of nickel into aluminum. It was shown that a milling time of 50%-75% t cr may be near optimal when taking into account both the increased ignition sensitivity of mechanical activated Ni/Al and potential loss in reaction energy for longer milling times. Ignition delays due to the formation of hotspots ranged from 1.2 to 6.5 ms and were observed to be in the same range for all milling times considered less than t cr . Combustion velocities ranged from 20-23 cm/s for thermally ignited samples and from 25-31 cm/s for impacted samples at an impact energy of 200-250 J.

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confidence: 98%

mentioning

confidence: 98%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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The role of microstructure refinement on the impact ignition and combustion behavior of mechanically activated Ni/Al reactive composites

Mason

Groven

Son

2013

Journal of Applied Physics

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Combustion Characterization of Energetic Fluoropolymer Composites

Mulamba¹,

Pantoya²

2014

Handbook of Fluoropolymer Science and Technology

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Reactive Structural Materials: Preparation and Characterization

Hastings

Dreizin

2017

Adv Eng Mater

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Reactive structural materials, which can serve both as structural elements as well as a source of chemical energy released upon initiation have emerged as an important class of metal-based composites for use in various energetic systems. Such materials rely on a variety of exothermic reactions, from oxidation to formation of metal-metalloid and intermetallic phases. The rates of these reactions are as important as the energy that may be released, in order for them to occur at the time scales compatible with the requirements of applications. Therefore, chemical composition, scale at which reactive components are mixed, and the structure and morphology of materials are important and can be controlled by the method of preparation and compaction of the composite materials. Methods of preparation of the composite structures are briefly reviewed as well as methods of characterization of their mechanical and energetic properties. In addition to common thermo-analytical and static mechanical property measurements, dynamic tests of mechanical properties as well as ignition and combustion experiments are necessary to understand the fragmentation, initiation, and heat release expected for these materials when they are stimulated by an impact, shock, or rapid heating. Reaction mechanisms are studied presently for the thin layers and small samples of reactive materials initiated in carefully designed experiments. In other experiments, impact and explosive initiation are characterized for larger material compacts in the conditions imitating practical scenarios. Examples of results describing thermal, impact, and explosive initiation of some of the reactive materials are presented.

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Impact sensitivity of intermetallic nanocomposites: A study on compositional and bulk density

Cited by 36 publications

References 15 publications

The role of microstructure refinement on the impact ignition and combustion behavior of mechanically activated Ni/Al reactive composites

The role of microstructure refinement on the impact ignition and combustion behavior of mechanically activated Ni/Al reactive composites

Combustion Characterization of Energetic Fluoropolymer Composites

Reactive Structural Materials: Preparation and Characterization

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