The electrical resistivity of 12Х18Н10Т stainless steel specimens was measured in the course of compression and heating under stepwise shock compression. A mathematical simulation of the obtained experimental data was conducted. The simulation allowed switching to specific values and reconstructing the volume–temperature dependence of the electrical resistivity of steel at high pressures of 25–65 GPa and temperatures of 350–950 K. Semi-empirical regularities were identified that permit the prediction of the total effect of a decrease in the electrical resistivity of 12Х18Н10Т steel upon compression and its increase upon heating. The outcomes of the electrical resistivity tests on shock-compressed and heated steel are evaluated in comparison with the existing literature data on similar experiments conducted under atmospheric pressure and high temperatures.

Experiments were carried out on multiple shock wave compression and subsequent storage of powdered samples of boron carbide. The samples were subjected to the stepwise shock compression. Steel-tungsten capsule was used for saving of shocked samples. The maximum pressures in the sample under study reached 70 GPa. X-ray phase analysis, electron microscopy, and X-ray spectral microanalysis of boron-carbide samples before and after loading were performed. It is shown that as a result of the impact of dynamic pressures P-tr = 63(7) GPa and temperatures T-tr = 1600(200) K, new reflexes appear on the X-ray diffraction patterns of the shocked boron-carbide samples, which are presumably due to the formation of graphite and tungsten borides. Assessment of the temperature and pressure at the beginning of physical and chemical transformations and melting of powdered boron carbide under stepwise shock compression is discussed.

In situ electrical resistivity measurements are performed on samples of iron with a hexagonal close–packed lattice (ε–Fe), compressed and heated by stepwise shock loading. Equations of state for ε-Fe are constructed. The obtained experimental results are mathematically simulated in the hydrocode based on the developed equations of state. The modeling results are used to reconstruct the volumetric–temperature dependence of the ε–Fe electrical resistivity at pressures of ≈20–70 GPa and temperatures of ≈750–950 K. The volume–temperature dependence of the ε-Fe thermal conductivity coefficient is calculated according to the Wiedemann–Franz law. The results obtained for the electrical and thermal conductivity of shock compressed and heated ε-Fe are compared with literature experimental and theoretical data for iron and silicon iron.

Abstract—The paper attempts to build equations of state of muscovite in the region of high pressures and high temperatures. This problem is solved by reconstructing the free energy of the crystalline and amorphous muscovite phases as analytical functions of the specific volume and temperature. Mutually consistent equations of state (thermal, caloric, Mie-Grüneisen) of each phase are constructed on the basis of general thermodynamic equations and partial derivatives of reconstructed semiempirical formulas for free energy. The reliability of the equations of state is justified by the agreement of some calculated and experimental thermophysical properties (compression, thermal expansion, bulk compression modulus, heat capacity, Hugoniot) of muscovite at pressures as high as ≈70 GPa and temperatures as high as ≈1700 K.

The microstructural characteristics of original textured tungsten samples are certified. The free surface velocities of the samples were measured in shock-wave experiments. The dynamic yield strength and spall strength values are determined for samples of various thicknesses. Mathematical modeling of the performed experiments is carried out within the hydrocode algorithm, in which original equations of state, an elastoplastic model, and an instantaneous spall approximation are used. The reliability and predictive capabilities of simulation of the physical and mechanical behavior of textured tungsten under conditions of shock-wave compression and high-speed tension are discussed.

A method for recording magnetic transformation is presented for ferromagnetic steels under shock-wave loading. The operation of the magnetic transformation gauge is considered under shock-wave loading at the polymorphic transition pressure of ARMCO iron and 15Kh2NMFA nuclear reactor case steel. It is shown that the pressures of magnetic transformations of steels correlate with the pressures of polymorphic transitions of these shocked steel. Comparison of the gauge readings and parameters of polymorphic transitions are performed for iron and steel during shock-wave compression and subsequent unloading.

A.M. Molodets A.A. Golyshev, A.N. Emelyanov, A.A. Kozlov The method for recording magnetic transformation is presented for ferromagnetic steels under shock-wave loading. The operation of the magnetic transformation gauge is considered under shock-wave loading at the polymorphic transition pressure of ARMCO iron and 15Kh2NMFA (in Russian) nuclear reactors case steel. It is shown that the pressures of magnetic transformations of steels correlate with the pressures of polymorphic transitions of these shocked steels. Comparison of gauge readings and parameters of polymorphic transitions was performed for iron and steel during shock-wave compression and subsequent unloading

We present a modification of the semiempirical description of the volume–temperature dependences of the electrical and thermal conductivities of α iron that has a body-centered cubic lattice. We consider an interpolation of the volume–temperature dependences of the resistivity and thermal conductivity of α iron along high-temperature isobars and high-pressure isotherms in the pressure range from –5 to +5 GPa at temperatures of 400–800 K, which correspond to the thermodynamic conditions of the standard and emergency functioning of iron alloys. The interpolation of the electrical and thermophysical properties of α iron is performed based on the developed equation of state of α iron at high pressures and high temperatures. The effect of compression and extension on the thermal conductivity of α iron is estimated.

Modification of the semiempirical description of the volume-temperature dependence of the electrical conductivity and thermal conductivity of alpha-iron (iron having a body-centered cubic lattice structure) is presented. The interpolation of the volume-temperature dependences of the resistivity and thermal conductivity of alpha-iron along high-temperature isobars and high-pressure isotherms in the pressure range from -5 GPa to +5 GPa and temperatures of 400-800 K is considered for the conditions of normal and emergency operation of iron alloys. The interpolation of the electro-and thermophysical properties of alpha-iron is performed on the basis of the developed equation of state of alpha-iron at high pressures and temperatures. the effect of compression and tensile pressure on the thermal conductivity of alpha-iron is estimated.

The aim of this work is to determine the melting temperature of boron carbide at high shock pressures. To this end, powder boron carbide samples have been compressed by shock waves with an amplitude of 60–80 GPa. Shocked samples have been recovered for the subsequent electron microscopy, X-ray spectroscopy, and X-ray diffraction analyses. The event of sample melting has been identified by the disappearance of boundaries between particles of the recovered initially powder sample. The pressure and temperature of shocked particles of boron carbide powder have been calculated using a hydrocode based on the previously developed equations of state for boron carbide and experimental setup materials. The average melting temperature of the boron carbide has been determined as Tml = 1900(500) K at the pressure Pml = 70(10) GPa.

Abstract Spall strength of zirconium heated by a strong shock wave to thousand-degree temperatures and that underwent transformations into denser polymorphic modifications was determined. Pressure profiles at the sample–soft barrier boundary were measured in spall experiments under flat one-dimensional loading. The equations of state of three polymorphic modifications of zirconium were constructed in the pressure range up to 50 GPa. Thermodynamic states of zirconium, which were calculated under conditions of experiments, in combination with results of measurements of pressure profiles, made it possible to determine the spall strength of zirconium heated in the shock compression–unloading cycle. The spall strength of zirconium was –2.8(7) GPa at 1027(70) K. Experimental pressure profiles were analyzed using the results of mathematical modeling of the performed experiments.

Spall strength of zirconium heated by a strong shock wave to thousand-degree temperatures and that underwent transformations into denser polymorphic modifications was determined. Pressure profiles at the sample–soft barrier boundary were measured in spall experiments under flat one-dimensional loading. The equations of state of three polymorphic modifications of zirconium were constructed in the pressure range up to 50 GPa. Thermodynamic states of zirconium, which were calculated under conditions of experiments, in combination with results of measurements of pressure profiles, made it possible to determine the spall strength of zirconium heated in the shock compression–unloading cycle. The spall strength of zirconium was –2.8(7) GPa at 1027(70) K. Experimental pressure profiles were analyzed using the results of mathematical modeling of the performed experiments.

Crystalline powder boron carbide samples are subjected to explosive loading by 2-μs shock waves with an amplitude of 38 GPa and shock heating to 700 K and to subsequent conservation. The samples recovered after shock-wave loading are studied by X-ray diffraction, and new effects of shock-wave loading on boron carbide are revealed. The explosive treatment is shown to shift the X-ray diffraction reflections of initial boron carbide toward high angles, which is attributed to an increase in the boron carbide density at the level of atomic volume in the unit cell of boron carbide. The X-ray diffraction reflections are found to broaden, which is interpreted as an increase in the coherent scattering region in the crystalline boron carbide subjected to the explosive treatment.

The spall strength and dynamic yield stress of polycrystalline hafnium have been measured in a series of plane-wave shock loading experiments using flat sample–transparent window composite targets, with the transparent windows representing polymethyl methacrylate or lithium fluoride plates arranged on the rear side of a hafnium sample. The front side of the target was subjected to shock impact of a copper striker, the rear surface velocity was measured, and the sample was recovered for subsequent metallographic examination. The results were also used for evaluation of the accuracy of spall strength measurements and the analysis of features of high-rate deformation of hafnium.

We determined the spall strength of hafnium heated by a loading shock wave to thousands of degrees and subjected to transformations into denser polymorphic modifications. To achieve this goal, the following tasks were solved. The pressure profiles at the interface between the sample and soft buffer material in the spall experiments with flat, one-dimensional loading are measured. The equations of state of three polymorphic modifications of hafnium are constructed in the pressure range up to 100 GPa. The thermodynamic states of hafnium were calculated under the conditions of the performed experiments, which, together with the results of measurements of pressure profiles, made it possible to determine the spall strength of hafnium heated in a cycle of shock compression–unloading. The spall strength of hafnium was –4(1) GPa at a temperature of 1680(380) K. The spall experiments were mathematically simulated in the framework of a one-dimensional hydrocode.

AbstractThe spall strength and dynamic yield stress of polycrystalline hafnium have been measured in a series of plane-wave shock loading experiments using flat sample–transparent window composite targets, with the transparent windows representing polymethyl methacrylate or lithium fluoride plates arranged on the rear side of a hafnium sample. The front side of the target was subjected to shock impact of a copper striker, the rear surface velocity was measured, and the sample was recovered for subsequent metallographic examination. The results were also used for evaluation of the accuracy of spall strength measurements and the analysis of features of high-rate deformation of hafnium.