FIRST-PRINCIPLES INVESTIGATION OF IMPACT-INDUCED OXIDATION OF REACTIVE MATERIALS

Abstract

The strain-dependent oxidation of metals for reactive material warheads is studied with quantum mechanical simulations. A two-stage surface oxidation process was investigated for Titanium, Copper, and Zirconium in unstrained condition and for isotropic compression and tension. The results show exothermic surface oxidation and an increased strain-sensitivity for the pyrophoric materials Titanium and Zirconium in comparison to non-pyrophoric Copper. While tension stabilizes the surface oxidation, compression leads to a destabilization of oxidized surfaces. The release of metal oxides from the oxidized surface is endothermic for all materials in unstrained condition. It was found that the release of metal oxides is stabilized by compression and can even be turned exothermic by sufficient lattice strain.