Dislocation–Assisted Initiation of Energetic Materials*

The role of dislocations in assisting initiation of (explosive) chemical decomposition of energetic materials has connection with the known influences for crystals and polycrystals of dislocations facilitating permanent deformations and phase transformations. X-ray topographic observation of relatively few dislocations in solution-grown crystals relates to the influence of large Burgers (displacement) vectors that are characteristic of molecular crystal bonding. Both model evaluations of the load dependence of cracking at hardness indentations and the derived hardness stress-strain behaviors show that dislocation movement is difficult whether in the indentation strain fields or at the tips of indentation-induced cracks. Thus, energetic crystals are elastically compliant, plastically hard, and relatively brittle [1]. Nevertheless, cracking is shown to be facilitated by the shear stress driven, normally limited, dislocation flow that, on molecular dynamics and dislocation pile-up model bases, is shown to be especially prone to producing localized hot spot heating for explosive initiations. Such model consideration is in agreement with greater drop-weight heights being required to initiat