Effects of Temperature and Pressure on Elastic Properties of Single Crystal Aluminum in Different Crystal Orientations

Molecular dynamics simulations are carried out to study the mechanical and elastic properties of single crystal aluminum with various crystal orientations at different temperatures and under different pressure. Transformations of lattice structures under high pressure, tensile and shearing loads are investigated, respectively. When the pressure increases to 1011 Pa, the face centered cubic (FCC) structure is completely transformed into body centered cubic (BCC) and other structures. The transformation from FCC to hexagonal close packed (HCP) and other structures takes place during tensile and shearing processes. Elastic compliance constants are calculated at different temperatures. Elastic modulus and shear modulus of different crystal orientations at different temperatures are calculated by the formula method, and compared with the results of molecular dynamics method. The decrease extent of elastic modulus in <111> crystal orientation is the smallest with the increase of temperature. The effects of high pressure on elastic modulus and shear modulus in different crystal orientations are also investigated. When the pressure exceeds 109 Pa, the elastic modulus and shear modulus in all crystal orientations begin to increase. Poisson's ratio in different crystal orientations at different temperatures and under high pressure are also calculated.