Analysis of Shock Compression Data for Porous Samples
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ICAL THERMODYNAMICS AND THERMOCHEMISTRY
Analysis of Shock Compression Data for Porous Samples D. K. Belashchenkoa,* a
National University of Science and Technology MISiS, Moscow, 119991 Russia *e-mail: [email protected] Received November 25, 2019; revised March 2, 2020; accepted March 17, 2020
Abstract—The literature data on shock compression of compact and porous samples of a number of metals (copper, tin, lead, bismuth, iron, and nickel) and the use of these data in calculations of interparticle potentials in the embedded atom model (EAM) were considered. The Hugoniot shock adiabats of compact metals provide information for calculations of EAM potentials, but as the porosity of the initial samples increases, they become unsuitable for this purpose because of inconsistency with the data obtained on compact samples. Possible reasons for this inconsistency were considered. Keywords: shock compression, porous samples, metals, interparticle potential, Hugoniot shock adiabats DOI: 10.1134/S0036024420100064
As is known, the set of data on shock compression of a compact metal under certain conditions in its initial state (at a pressure p1 and molar volume V1) allows one to obtain a single Hugoniot shock adiabat. The latter is described by the equation [1, 2]
ΔU = (1/2)( p1 + p2 )(V1 – V2 ),
(1)
where p1 and p2 are the initial pressures ahead and behind the front of the shock wave, V1 and V2 are the molar volumes of the metal ahead and behind the wave front, and ΔU = U2 – U1 is the difference in the molar energies of the metal behind and ahead of the wave front. On the (V, p) plane, the shock adiabat forms a trajectory. Other points of the quadrant V, p are inaccessible from the same starting point. If the metal in the initial state is in the standard state (T = 298 K, p1 = 1 atm, and V1 = V0 is the standard molar volume), this adiabat is called the main adiabat. However, it is possible to use in the initial state a metal with properties other than standard: initially porous, cooled, heated, or liquid. Then we can construct a family of shock adiabats that issue from different points of the quadrant V, p and cover a wider range of states [2]. Equation (1) remains valid for porous substances [1, 2]. The first studies on shock compression of metals appeared in the 1950s. A significant number of works were performed using initially porous samples. Russian studies in this direction have been performed since 1958 until recently [3]. Foreign publications on compression of porous metals appeared mainly over the period from 1968 to 1980. The degree of initial porosity is usually described by the coefficient m = V00/V0, where V0 is the standard molar volume,
and V00 is the actual initial molar volume. For the initially porous substance, m > 1. According to the rich information given at the site [4], m values from 1 to 10–20 were used. During shock compression of a porous material, significantly higher temperatures can be obtained than during compression of a compact metal. The data obtained by shock compression are of interes
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