Theoretical Strength of Perfect Crystalline Materials

摘要

A mathematical procedure is presented for applying the Born stability criteria to the determination of the mechanical stability of cubic crystals in the presence of applied forces and deformations. The general procedure is suitable for use in conjunction with a computer and is independent of the specific model of interatomic interactions that can be used in numerical calculations. Specific calculations are performed for a body-centered cubic (B.C.C.) crystal lattice with a uniaxial tensile force applied perpendicularly to a face of a unit cell. The atoms in the crystal are assumed to interact through a 2-body Morse interatomic potential function appropriate to B.C.C. iron. Two ranges of stability are found to exist: a B.C.C. phase and body-centered tetragonal phase (B.C.T.). For the B.C.T. phase, the lattice remains stable for values of tensile strain up to about 7%, with corresponding strength. These values are close to the measured tensile characteristics of fine iron whiskers. (Author)