Generation of Defects during Shock Compression of Aluminum

Abstract

Measurements of the electrical resistance of shock-compressed aluminum are used in the present study to estimate the concentration of point defects generated by the shock wave front. The parameters of the physical state of a thin metal sample are found by means of modeling the shock wave processes in the measurement cell. Experimental values of the specific electrical resistance of aluminum are compared with predictions of the equilibrium electrical resistance model. The proposed model ensures an adequate description of currently available reference data on equilibrium isothermal compression and isobaric heating of aluminum. At the same time, the shock wave experiment yields a higher specific electrical resistance than that predicted by the model of the electrical resistance of an equilibrium defectless crystal. The detected difference in the specific electrical resistances testifies to generation of defects of the crystal structure of the metal subjected to dynamic compression. Under the assumption of predominant formation of vacancies, the concentration of defects in aluminum is estimated as a function of the shock wave pressure. The number of defects in the metal increases with an increase in the shock wave pressure. The data obtained are qualitatively consistent with available results for copper and silver, which allows one to claim that generation of defects under shock compression has common specific features for these metals. The physical state of shock-compressed aluminum is thermodynamically nonequilibrium and includes numerous defects.