Measurement of Shock Residual Temperature in Steel with the Help of phase Transitions in Zirconium and Titanium

The phase structure of recovered zirconium and titanium samples was studied after loading by plane shocks waves in steel ampoules up to pressure 8-32 GPa. Beginning from some critical pressure residual heating results in full decomposition of the [MATH]-phase. This fact is the basis of evaluation of residual temperature. Obtained values of residual temperature in steel 240 - 500°C in an interval of pressure 23 - 32 GPa turned out to be much higher than values, obtained from temperature calculations usually used for shock waves.On a étudié la composition de phase du zirconium et du titane ohtenue sous pression après la mise en charge d'échantillons entre 8 et 32 GPa créée par des ondes de choc planes. A partir d'une pression critique, la ternpérature résiduelle dégrade totalement la phase [MATH]. Ce résultat a été pris comme base pour l'estimation de la température résiduelle. Les valeurs de la température résiduelle pour l'acier ont été mesurées entre 240 et 500°C dans la gamme des pressions des 23 à 32 GPa

Influence of preloading on formation of adiabatic localized shear in copper

This paper is devoted to results of investigation of localized shear in as-received copper, and which was subjected to preliminary quasi-isentropic shock loading by the pressure of ∼ 30 GPa. Tests were performed with hat-shaped samples by the Split Hopkinson Pressure Bar method (SHPB). The authors present estimation of quantitative characteristics of localized shear in tested materials (shear stress, relative shear strain, shear band width, relative strain rate in shear band). The paper includes data of metallographic investigations of the tested samples. Also the authors made an attempt of numerical simulation of stress field change during formation

Study of phase transitions in cerium in shock-wave experiments

Cerium has a complex phase diagram that is explained by the presence of structure phase transitions. Planar gauges were used in various combinations in experiments for determination of sound velocity dependence on pressure in cerium by the technique of PVDF gauge. The data of time dependence on pressure profiles with use of x(t) diagrams and the D(u) relation for cerium allowed the definition of the Lagrangian velocity of the unloading wave CLagr and the Eulerian velocity CEul by taking into account the compression σ. These results accords with data obtained by using the technique of VISAR and a manganin-based gauge, and calculated pressure dependence of isentropic sound velocity according to the VNIITF EOS. Metallography analysis of post-experimental samples did not find any changes in a phase composition

Spall fracture of copper under loading by shock waves with duration less 1 microsecond

The paper presents results of experimental researches on spall fracture of polycrystalline copper when loading by shock waves with intensity of 20–33 GPa and duration < 1 μs. It is shown that decrease of copper spall strength is observed behind SW front at SW intensity of ∼ 33 GPa (above threshold of formation of heterogeneous deformation bands). When reducing SW intensity to 27 GPa, spall strength is restored. Duration of the softened copper state does not exceed ∼ 0.5 μs. The method for spall strength evaluation is based on measurement of maximum damage in post-test samples

Spall fracture of copper under loading by shock waves with duration less 1 microsecond

The paper presents results of experimental researches on spall fracture of polycrystalline copper when loading by shock waves with intensity of 20–33 GPa and duration < 1 μs. It is shown that decrease of copper spall strength is observed behind SW front at SW intensity of ∼ 33 GPa (above threshold of formation of heterogeneous deformation bands). When reducing SW intensity to 27 GPa, spall strength is restored. Duration of the softened copper state does not exceed ∼ 0.5 μs. The method for spall strength evaluation is based on measurement of maximum damage in post-test samples

Study of phase transitions in cerium in shock-wave experiments

Cerium has a complex phase diagram that is explained by the presence of structure phase transitions. Planar gauges were used in various combinations in experiments for determination of sound velocity dependence on pressure in cerium by the technique of PVDF gauge. The data of time dependence on pressure profiles with use of x(t) diagrams and the D(u) relation for cerium allowed the definition of the Lagrangian velocity of the unloading wave CLagr and the Eulerian velocity CEul by taking into account the compression σ. These results accords with data obtained by using the technique of VISAR and a manganin-based gauge, and calculated pressure dependence of isentropic sound velocity according to the VNIITF EOS. Metallography analysis of post-experimental samples did not find any changes in a phase composition