Equations of state for metals (Al, Fe, Cu, Pb), polyethylene, carbon, and boron nitride as applied to problems of dynamical compression

Abstract

Metals (Al, Fe, Cu, Pb), polyethylene, and other plastic materials with a density of about 1 g/cm3 are commonly used as liners and screens in solving dynamic-compression problems that involve phase transitions. In this paper, the equations of state are presented in the form of formulas, graphs, and tables for the pressurep and energyE as functions of temperatureT and density ρ. These equations have a meaningful theoretical form and are based on the measured initial sound velocityc 0, densityρ 0, Gruneisen parameter Γ, heat capacityc p, sublimation energyU evp, and the known pressure dependence of the compression modulus ϱK/ϱp. These equations of state are in satisfactory agreement with available experimental data on shock compression. According to the same scheme, the equations of state are derived for carbon and boron nitride. However, in this case, the situation turned out to be much more complicated due to the existence of phase transitions from the hexagonal form into wurtzite and cubic forms. In deriving the equation of state, the equilibrium curve between the graphite-like and diamond phases on the phase diagram was additionally used. As a result of realization of the aforementioned scheme, the equations of state obtained (i.e., formulas, graphs, and tables) are in satisfactory agreement with experimental data.