On Nanosecond Thermophysics (Review)
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MOPHYSICAL PROPERTIES OF MATERIALS
On Nanosecond Thermophysics (Review) G. I. Kanel’* Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, 125412 Russia *e-mail: [email protected] Received March 10, 2020; revised March 19, 2020; accepted March 30, 2020
Abstract—A review of highly nonequilibrium states generated in solids and liquids by a short shock-wave action is presented. States with large deviator stress components, large negative pressures, overheating of the solid phase, supercooling of the liquid phase, and issues of viscosity of liquids (including metal melts) and solids at strain rates up to 108 s–1 and high pressures are considered. The dynamic tensile strength (cavitational strength) of metal melts, fast polymorphic transformations, and a new rule for selecting the detonation velocity of explosives are discussed. DOI: 10.1134/S0018151X20040057
CONTENTS Introduction Methods and directions of experimental research Ultimate states upon short-term exposure Shock-wave width and viscosity of solids and liquids Dynamic strength of liquids Abnormal compressibility, rarefaction shock waves, polymorphic transformations New rule for the selection of the detonation velocity Conclusions References INTRODUCTION First, two explanations need to be made. Nanosecond thermophysics is a catchy name, but the subject of this work includes phenomena and processes ranging from picoseconds to microseconds in duration. The combination of the concepts of “time” and “thermophysics” in this review refers to the possibility of achieving highly nonequilibrium states and the study of the kinetic laws of the equilibration processes. Strong actions in the indicated range of durations and, accordingly, highly nonequilibrium states of matter are implemented during a high-speed impact or explosion or upon exposure to powerful short-time pulses of laser or particle radiation. The properties of matter under these conditions are of interest not only for defense and aerospace engineering but also for some technological processes; for example, the achieved deformation rates in material cutting fall within the range of parameters discussed in this review. Studies of the properties of a substance under the indicated conditions are mainly carried out with methods of shock-wave physics. This review is focused on the information obtained in the analysis of shock-
wave phenomena in condensed matter. The beginning of shock-wave methods was associated with the need to obtain experimental data on the equations of state of substances in the megabar pressure range for the design of an atomic bomb [1–3]; record high pressures are still obtained and studied with dynamic methods. Compressions to high pressures take place inside planets and stars and can be achieved for a long time under laboratory conditions with the use of, e.g., diamond anvil cells, while extremely nonequilibrium states, including large negative pressures, can only be studied with dynamic methods. In contrast to the hydrostatic compression of a substance, deviations
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