The effects of thermal friction, associated with the interaction between mobile clusters of interstitial atoms produced in collision cascades and phonon excitations, were investigated. Phonons gave rise to a random Brownian motion of clusters in the crystal lattice. Phonon excitations were also responsible for the dissipation of the energy of rapidly moving clusters which formed at the periphery of collision cascades. The way in which the coefficient of thermal friction depended upon the structure of clusters was investigated. The results had implications for understanding the origin of the higher resistance of body-centered cubic metals to irradiation, and the connection between this phenomenon and the long-range effect observed in experiments on ion implantation.

Effect of Thermal Friction on the Generation and Transport of Interstitial Defects in Irradiated Metals. S.L.Dudarev, J.R.Matthews: Nuclear Instruments and Methods in Physics Research B, 2002, 193[1-4], 253-8