Molecular Dynamics Of The Phase Transition In Single-crystal Al、Fe Induced By High-pressure

With the rapid development of computer, computer simulation method can obtain important information of material microstructure which is difficult to get at the experiments, so more and more people pay attention to it. And it is helpful to the development of theory and experiment. And aluminum and iron have been widely used in daily life and industry, so the study of high pressure phase transition is of significance.In this paper, molecular dynamics simulation is used to investigate the structure transformation of single crystal Al and Fe, the structural phase transition is induced by uniform compression. And phase transformation mechanism is mainly discussed. It contained change regulation of pressure, temperature and formation characteristics of the new phase. The radial distribution function and coordination number method were used.In our simulation, the single crystal Al occurred fcc-bcc structure transformation, and the results indicated that the transition pressure is about270GPa, volume is reduced to about0.55V0, and it is in reasonable agreement with the calculated value through density functional. When the structure transformation was finished,(Oil),(101) and (-110) interfaces were primary crystal boundary of bcc structure. The single crystal Fe occurred bcc-hcp structure transformation, and the transition pressure is about28.5GPa. With different strain, the change trend of samples pressure were similar, that was, initial stage of relaxation will appear abrupt, then the pressure would down to a certain value with reaching equilibrium, and the equilibrium pressure increases with increasing strain; With strain increasing, the time of sample producing phase transition is shorting and the number of HCP atoms is reducing, while FCC phase atoms can reach40%, when the strain is0.1694, the mass fraction of FCC is more than the mass fraction of HCP phase, which indicates that the adjacent atomic interlayer slipped.