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Reactive Metals

The Research

While traditional energetic materials have many and varied uses, there are a number of things that they are rather poor at, for example it is very difficult to make structural components from them. One potential way around some of these limitations is to make components out of reactive metal components. Currently this subject is the focus of a large number of research programmes across the world, and to date the group has been involved in two separate initiatives to examine metallic reactions and the mechanical properties of reactive metal mixtures.

The first project was to examine the performance of systems containing powdered nickel and aluminium. This involved examining the microstructures formed when these materials are pressed together to different densities, looking at their mechanical properties and finally examining the reactivity. This project utilised a very wide range of the experimental apparatus within the group, including the Inston, Hopkinson Bars, gas guns and high speed cameras. Modelling work was also carried out by QinetiQ to link in with the experimental effort.

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Two micrographs showing unreacted (top) and reacted (bottom) microstructure in a shock loaded nickel-aluminium powder bed.

The second project was involved collaborations with academic partners from UCSD, Georgia Tech and Johns Hopkins (see below). The main focus of this project was to examine how different manufacturing techniques for reactive metal combination would affect mechanical properties, and specifically fragmentation properties. The research was into a number of metallic combinations with the aim either of forming intermetallics, or enabling the rapid combustion of aluminium though fragmentation to a very small scale. Manufacturing techniques examined included cold and hot isistatic pressing, swaging, gas dynamic cold spray and explosive compaction. Much of the research involved examining materials under explosive loading and obtaining both time resolved photographic and velocimetry data as well as allowing for soft capture of fragments post experiment.

High speed image of fragmentation in metal sample after explosive loading.

 

The People

The majority of the research in the this area has been conducted by Dr. Chris Braithwaite. Important Academic collaborations have been formed with Prof. Vitali Nesterenko and Prof. Marc Meyers at UCSD, Prof. Naresh Thadhani at Georgia Tech and Prof. Tim Weihs at Johns Hopkins.

The Impact

Work conducted in the group in conjunction with QinetiQ lead to the development of a reactive metal shaped charge jet line which has subsequently been put into production by GeoDynamics.