RESUMO

Elastic, plastic, and cracking indentation measurements obtained in nano- to micro- to macroindentation hardness tests of ammonium perchlorate (AP) and cyclotrimethylenetrinitramine (RDX) crystals are usefully described on a hardness stress−strain basis and are assessed in terms of the dislocation pileup avalanche mechanism for hot-spot generation associated with sudden crack formation. The model considerations lead to interpretation of a particle size influence on the drop-weight height for 50% probability of onset of reaction, now extended to include recently reported results for ε-hexanitrohexaazaisowurtzitane (ε-HNIW) crystals. These considerations are extended to deformation of individual or interacting groups of crystals when incorporated within a composite formulation and in relation to the potential brittleness of the binder material if undergoing transition to a glassy structure.