A study was made of the diffusion of self-interstitial atoms and self-interstitial atom clusters in V via molecular dynamics simulations with an improved Finnis–Sinclair potential (fitted to first-principles results for self-interstitial atom structures and energetics). The present results demonstrated that single self-interstitial atoms existed in a <111> dumb-bell configuration and migrated easily along <111> directions. Changes of direction through rotation into other <111> directions were infrequent at low temperatures, but became prominent at higher temperatures; thereby changing the migration path from predominantly 1-dimensional to almost isotropically 3-dimensional. Self-interstitial atom clusters (i.e., clusters of <111> dumb-bells) could be described as being perfect prismatic dislocation loops with Burgers vectors and habit planes of ½<111>{220} that migrated only along their glide cylinder. Self-interstitial atom clusters also migrated along <111>-directions, but did not rotate. Both single self-interstitial atoms and their clusters exhibited a highly non-Arrhenius diffusivity, which originated from a combination of a temperature-dependent correlation factor and the presence of very low migration barriers. At low temperatures, the diffusion was approximately Arrhenius while, above room temperature, the diffusivity was a linear function of temperature.

Self-Interstitial Transport in Vanadium. L.A.Zepeda-Ruiz, J.Rottler, B.D.Wirth, R.Car, D.J.Srolovitz: Acta Materialia, 2005, 53[7], 1985-94