Theory of dislocation-creep due to the frenkel defects or interstitialcies produced by bombardment with energetic particles

Abstract

When, a material is subjected to stress whilst being bombarded with a flux of energetic particles it often creeps at a temperature-independent rate which varies with the product of flux and stress. The present paper shows that this simple class of behaviour is, theoretically, to be expected in materials containing a three-dimensional network of dislocations that absorb interstitials ('I-creep') or interstitials plus vacancies ‘F-creep'). The dislocations climb into positions where they can bow out until their curvature produces an opposing force virtually equal to that due to the external stress. From the Mott—Friedel equation for dislocation-bowing the resultant creep strain has been calculated and proves to be comparable in magnitude to that measured experimentally.