Basic Principles of Shock Compression

The ideas developed in this chapter are descriptive of shock waves in fluids. Solids have many significant features that distinguish them from liquids and gases, such as shear strength, polymorphic phase transformations, heterogeneous structure, anisotropy, and viscoplastic behavior. The influences of these special properties of solids on shock compression are the topics of several of the other chapters, and for the most part are ignored in this introduction to the basic principles of shock compression. 

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The chapters presented by different experts in the field have been structured to develop an intuition for the basic principles by discussing the kinematics of shock compression, first from an extremely fundamental level. These principles include the basic concepts of x-t diagrams, shock-wave interactions, and the continuity equations, which allow the synthesis of material-property data from the measurement of the kinematic properties of shock compression. A good understanding of these principles is prerequisite... 

The above-mentioned phase transitions conform to the Le Chatelier principle, the sample volume decreasing under high pressure. They are not basically different Irom those observed in the static method, under conditions of thermodynamic equilibrium. There is, however, a class of anomalous phase transitions, which occur only in dynamic experiments and in which the shock compression gives rise to lower densities. The first of such phases was obtained in 1965 by shock treatment of the turbostratic BN [224] the new phase differed from both the graphite-Uke (/i-BN) like (c-BN) polymorphs of boron nitride and was named E-BN (E standing for the explosion phase ). Later, it appeared that the lattice parameters of E-BN are nearly identical to one of the phases of fullerene Ceo [225, 226], viz. a = 11.14, ft = 8.06, c = 7.40 A for E-BN, cf. a= 11.16, = 8.17, c = 7.58 A for Qo, with similar densities of 2.50 g/cm. Thus, the BN-fullerene was obtained by explosion (though not recognized as such) some 25 years before the carbon fuUerene was identified. Later on. 

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