Abstract
A dynamic (cascade-probability) model for calculating the threshold displacement energy of knocked-out atoms (E d ) was proposed taking into account the influence of the instability zone (spontaneous recombination). General expression was recorded for Ed depending on the formation energy of interstitial atoms E f and vacancies E i , on the energy transfer coefficient α and the number of interactions i needed to move the atom out of the instability zone. The parameters of primary particles were calculated. Comparison of calculations with experimental data gives a satisfactory agreement.