Mechanistic aspects of impact initiated reactions in explosively consolidated metal+aluminum powder mixtures

The mechanisms influencing impact initiation of reactions in structural energetic materials formed by explosive compaction of pure Ni, Ta, or W powders mixed with Al powder are investigated in this work. High speed images of rod-on-anvil impact tests indicate that the energy requirements for initiating reaction in Ta+Al compacts are lower than those in W+Al, while no reaction at all is observed in Ni+Al under the tested conditions. Mesoscale simulations performed on actual microstructures reveal differences in the deformation behavior of the Ni+Al, Ta+Al, and W+Al compacts under similar impact conditions. In the Ni+Al and W+Al systems, the impact induced deformation is localized primarily in the Al constituent, while significant plastic deformation of both constituents is observed in Ta+Al, making it a more reactive system.