Effects of Microstructure on Explosive Behavior

Abstract

L IntroductionI T is almost axiomatic that the macroscopic behavior of a material is strongly dependent on its microstructure. This is especially true for explosives, where variations in microstructure have a marked effect on many aspects of reactivity that affect safety, handling, and performance. Although the importance of effects of microstructure on certain aspects of explosive behavior has been well known for many years, a thorough and accurate description of the relationship between explosive behavior and microstructure still eludes us. This review is intended to summarize our current understanding of this relationship and to indicate directions for further research. Although the review is intended to focus primarily on the influence of microstructures on macroscopic behaviors, there are certain behaviors in between the microstructural and macrostructural that need to be addressed, and these are discussed as well. Further, some attention is given to the macroscopic behaviors that are believed to be sensitive to microstructural effects.Examples of explosive behaviors that are believed to be quite sensitive to microstructural effects are shock sensitivity, fragment impact sensitivity, thermal (cookoff) response, friction response, and response to low-velocity impact. In this chapter, we address each of these in turn, although not at the same level of detail. The level of detail will be partly driven by the extent to which researchers have explored microstructural effects and partly by the importance of microstructures to the explosive behavior. (The role of microstructure in shock initiation behavior has been much more thoroughly investigated than the role of microstructure in cookoff behavior, for example. Also, the influence of microstructural features on various forms of sensitivity is typically much greater than its influence on performance.)