536.424The results of experiments [1, 2] show that the kinetics of phase transitions of some forms of H 2) into others play an important role in the formation of the complex wave patterns that arises when ice is subjected to an explosion or a shock. Thus, according to the data presented in [1], in the 150-200 MPa pressure range ice I begins to melt, at pressures from 200 MPa to 500 MPa a mixture of ice I and water is formed, and at pressures from 600 MPa to 1700 MPa the final phase is ice VI (the experiment was carried out on a specimen of ice I at a temperature T = (263 + 2) K). If we take into account the fact that under thermodynamic equilibrium conditions the regions in which ice I can exist in the 240-273 K temperature range is limited to pressures of the order of 200 MPa, the beginning of this phase of ice up to a pressure of 500 MPa confn'ms that phase transitions in ice are of a nonequilibrium character.The general principles for describing condensed media with phase transitions, based on the laws of the thermodynamics of irreversible processes, on certain models of the kinetics of phase transitions are presented in [3]. An approach to describing two-phase media wlth a phase transition, proposed in [4], was generalized in [5] to the case of N coexisting transformable phases and was used to investigate the shock loading of bismuth. A review of the results of theoretical and experimental investigations on phase transitions for the case of shock-wave loading of materials can be found in [6, 7].In this paper we carry out a theoretical investigation of the loading of ice taking the kinetics of the phase transitions into account. The thermal equations of state and the thermodynamic properties of ice I, III, V, and VI and water, established previously in [8, 9], are used to describe the rapid loading of ice and the dynamics of the phase transitions. The theoretical results obtained are compared with experiment.1. p-T-Diagram of It20 and Model of a Multiphase Medium. To investigate the loading of ice, taking kinetic effects into account, we will take the temperature T and the Pressure p as the independent variables. In Fig. 1 we show a p-T phase diagram of H20 in the temperature range 240 <_ T _< 300 K and pressure range 0 _< p _< 103 MPa. We will denote the set of (p, T) points corresponding to Fig. 1 by ft. The results of a detailed study of the thermodynamic properties of ice and water in these pressure and temperature ranges are given in [8, 9]; the thermal equations of state of ice I, III, V and VI and liquid water were obtained, and their thermodynamic properties were also established. These results are used to investigate the effect of the kinetics on the loading of ice.Following [9], we will denote quantities relating to ice I, III, V, VI and water by the symbols 1, 3, 5, 6, and w respectively. We will denote the set of symbols by ~I,, we will denote the region i (i E ~I,), in which a thermodynamically stable phase exists by f~i, and we will denote the lines of phase transitions by a pair of indices writ...
