Dislocation loops at twin boundaries in an ion-irradiated austenitic alloy

Abstract

Dislocation loops having a three-lobed shape have been observed at coherent twin interfaces in an ion-irradiated austenitic alloy. The specimens were implanted with 380 keV Cr⁺ and 40 keV He⁺ ions at 600°C and the loops formed both in the matrix and at the twin boundaries were found to be interstitial in nature with Burgers vectors of the type α/3〈111〉. The presence of a loop-denuded zone at twin interfaces provides evidence for a significant interaction between interstitials and the coherent twin boundary. The loop shape has been interpreted in terms of the relative rates of diffusion of point defects along the dislocation line and in the twin interface.