The Coexistence of Unstable, Metastable, and Separated Frenkel Pair Defects in Solids. II. Theory of the Impact Mechanisms for Defects Formation in Metals

Abstract The coexistence of unstable, metastable, and separated Frenkel pair defects in metals under nonequilibrium conditions generated via impact displacement of lattice atoms by incident particles is studied theoretically. The extent of a spontaneous annihilation (SA) zone of defects along their attraction directions is determined in the framework of elasticity theory. The value of defect formation threshold energy (DFTE) along the basic crystallographic directions is calculated and the degree of DFTE anisotropy is found. The displacement probability function and the damage function depending on the kinetic energy E of knock‐on atoms, the scattering law of colliding atoms, and the degree of DFTE anisotropy are obtained. The damage function found differs essentially from the well‐known Kichin‐Pease formula. It is shown that the cascade multiplication of defects is possible at E ≧ Ed, max ≈ 3 × Ēd (where Ed, max and Ēd are the maximum and average values of DFTE, respectively). The damage function found takes also into account the SA effect of metastable and separated pair components at overlapping of their existence zone with the SA zone of another partner. This effect is noticeable especially at low knock‐on energy. The results obtained are in good agreement with the experimental data.

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