Discussion For The Semi-empiric Equation Of State Of Metals

The equation of state (EOS) of metals can be described commendably by the so-called trinomial EOS which have 'the cold part', the thermal part contributing by crystal (or atoms) and the thermal part contributing by electrons. The most credible method to get this EOS is to choose appropriate functions of the three parts and use them to fit the experimental data. The EOS getting by this method is so-called the semi-empiric EOS.The essential aims of this paper are two, the first is to exposure the questions of the conventional results, the second is attempt to set up a new method which can simply to use and easy to get a reason result.In chapter 2, 4 kinds of P_c and 3 kinds of method to get the P_c have been discussed. The P_c refers to the OK isotherm. There are 5 primary results. (1) 'The Born-Mayer P_c and 'the Morse P_c '. (2) When to use the Morse potential, not less than 50 distinctions atoms must be calculated. (3) The precision of the 'universal energy function' by J. H. Ross for various metals maybe not equally. (4) There is a conflict between the shock compression experimental and the P_c got by using binding energy and isotherm bulk modulus. (5) Especially, a method to get P_c has been developed based on the formerly work by Hu Jinbiao. Many P_c of metals have been calculated by this method and been compared with literature and experimental data. It has been proved preliminarily that though this method is very simple and very easy to use, its result is in faith reason.In chapter 3, three aspects have been discussed to the Griineisen parameters γ . The fisrt is various definitions of γ and their relation. The primary results are two. (1) The γ got by experiment may contain thermal contributing by electrons and this part is not can be ignored. (2) γ got by thermal dynamic experimental data under normal temperature and pressure can be a standard for various theoretical models, but its precision should be analysis carefully before to use. (3) The method of using the Migault's formular associate tuning up parameter to express γ which often be used is not very reasonable. The second, the molecule dynamic method (MD) has been used to investigate the nature of γ at high temperature and pressure. The primary results is (4) that γ is really a reduced minorant but not a continuous function of temperature ?there a interrupt where material transfer its state from solid to liquid. The third, some methods which to get γ directly by experiments and their results have been discussed. The primary results are two. (5) The ability of carry out a porous shock compression experiments with uncertainty less than 20% has been had, and then there is apossibility to obtain γ at high pressure with uncertainty less than 10%. (6) Another method to get γ , utilizing the method 3 P_c and shock compression data, has been investigated. It has been shown preliminarily that there a simple phenomenal project to calculate γ by utiliaing this method.In chapter 4, the physics foundation of the 'WJ EOS' has been studied. This EOS is thought a supplement to the Gruneisen EOS for it utilizing pressure P and temperature T as its variables. A statistical mechanics proof had been presented, so the substance parameter R in the EOS first time has its virtual definition and then can be used without any other EOS. Additional, some other points of this EOS also have been discussed, for example, the R=R (p) hypothetic.