Numerical analysis on elastic properties of beryllium under high pressure or high temperature

Based on plane wave pseudo-potential in the framework of density functional theory (DFT), first principle calculations were performed to investigate elastic properties of beryllium for hexagonal close packed (hcp) structure (α-Be). The generalized gradient approximation (GGA) was adopted in concrete calculation in using CASTEP code of Material Studio program. The elastic constants of monocrystalline beryllium, the bulk modulus, shear modulus, Young's modulus and Poisson's ratio of polycrystalline beryllium were calculated under the condition of hydrostatic pressure in the range of 0 to 100 GPa. The same work mentioned above was also finished under the condition of environment temperature varying from 0 to 1300 K. First principle numerical simulations were also performed to investigate elastic properties of beryllium for body centered cubic (bcc) structure (β-Be). Calculation results were in good agreement with those experimental data obtained from references. Results showed that the elastic constants increased monotonically with pressure increasing, but decreased with temperature increasing monotonically; C12 and C13, describing deformation coupling along different directions, were more sensitive than the other elastic parameters to the changes of pressure or temperature; pressure increase made the value of beryllium lattice structure parameter c/a increase and approach to the ideal close packed value, while in temperature increasing process, this value deceased steadily. Pressure increase was a process of raising the density of atom packing, based on this understanding, the possibility and actualizing form of hcp-fcc (face centered cubic) phase transformation under high pressure were discussed. � Editorial Office of Chinese Journal of Rare Metals. All right reserved.