Hugoniot Curves of Metals

Abstract

Scientific investigation of shock parameters of metals, and primarily of their shock compressibility, was initially related to the problem of designing nuclear weapons. In the United States, experiments of that kind were started in 1945, and two years later the compressibility of uranium at pressures up to 50 GPa was first measured in Russia. For a long time thereafter work was done to refine the measured position of shock-compression curves (Hugoniots) for materials which had already been studied and to extend the range of pressure investigated. This is because a great many scientific and technical problems are currently solved on the basis of knowledge of shock properties of various materials. These include problems of high-velocity impacts, in particular of spacecraft and meteorite protection, the inner composition of the Earth and of other planets, verification of theoretical models of material behavior under extreme loading conditions, synthesis of novel materials, high pressure chemistry, etc. In 1995, as a result of work done to increase the range of pressure open to investigation, laboratory shock generators driven by high explosives were built and used in Russia to generate pressures higher than 2.5 TPa in heavy metals. Those pressures were approximately two-fold higher than those produced earlier in our country and five-fold higher (for the same materials) than pressures produced in research centers of other countries. Even higher pressures, up to 10 TPa, were generated in underground nuclear tests. Both these values were measured by the so-called absolute investigation technique. When this technique is used, the accuracy with which kinematic and thermodynamic parameters of material compression are determined depends only on the accuracy of the experiment itself and not on the validity of additional assumptions.