Mobility of self-interstitial atom clusters in vanadium, tantalum and copper

Molecular dynamics (MD) simulations were performed to investigate the mobil ity of isolated self-interstitial atoms (SIAs) and their dusters in V, Ta a nd Cu. The migration of an isolated SIA is accompanied by rotation of a dum bbell axis to the close-packed direction of metals. The migration of an SIA cluster strongly depends on its structure. A relatively smaller-size clust er can migrate with simultaneous rotation of the axes of SIA pairs in the c luster to the same close-packed direction, which is the glissile configurat ion of the cluster. The transformation to the glissile configuration takes place more frequently than the dumbbell rotation of an isolated SIA in V an d Ta, while it takes place less frequently in Cu. The smaller cluster can s till change its diffusion direction. A greater-size cluster in the bcc meta ls, on the other hand- has the thermally stable form of densely-packed, par allel crowdions. It migrates without any changes of diffusion direction. Th e migration behavior of 7-SIAs clusters in Ta was also evaluated as a funct ion of tensile and compressive strains. (C) 2001 Elsevier Science B.V. All rights reserved.