Title: Wide-range, Multi-phase Equation of State for Metals
 
Speaker: Igor V. Lomonosov, Institute for Problems in Chemical Physics of the Russian Academy of Sciences, Chernogolovka, RUSSIA
                              
Date/Time: Wednesday, October 19, 2005, 9:00-10:00 am

Location: Building 960, Room 1001B (Sandia NM)

Brief Abstract: I will discuss the high pressure and high temperature phase diagram of metals, and general problems of equation of state (EOS) construction. It is pointed out that the available high pressures, high temperatures information covers a broad range of the phase diagram, but has a heterogeneous character and, as a rule, is not thermodynamically complete; its generalization can be done only in the form of a thermodynamically complete EOS.

Principles of EOS construction are described using as examples the quasi-harmonic model of solids and the Mie-Grueneisen EOS. The extension of Mie-Grueneisen EOS to regions of high temperatures and low densities, and methods of taking into account effects of melting and evaporating are discussed.

I present a multi-phase EOS model accounting for solid, liquid, gas and plasma states, as well as two-phase regions of melting and evaporating.  The thermodynamic properties of metals and their phase diagrams are calculated with the use of this model; typical examples for nickel and uranium are presented.  Theoretical calculations of thermodynamic properties of the solid, liquid, and plasma phases, and of the critical point are compared with results of static and dynamic experiments.

I discuss our determination of the high pressure melting and vaporization curves, which were developed using direct temperature measurements and indirect information on phase transitions resulting from shock-wave experiments. These include measurements of sound velocity in shocked metals, principal Hugoniots of cooled and heated metals, porous metal Hugoniots and release isentropes. Conclusions are made for high-pressure melting and vaporization, as well as calculated parameters of the critical point parameters.

General regularities obtained from the analysis of 30 metals are presented.  The correspondence between Isobaric Expansion Experiment (IEX) and shock-wave data in the liquid is demonstrated for the metals investigated.  Birch’s law for liquid metals and its applicability are discussed.  Accurate EOS calculations are presented for possible applications of heavy-ion beam for high-energy-density physics.  Application of multi-phase EOS concerns the problem of shock-wave stability in metals is alluded to.