Multiscale characterisation and modelling of substructure evolution during plastic deformation of commercially pure niobium

Commercially pure Nb mono- and polycrystals were severely plastically deformed by ECAP. EBSD and TEM were used for characterizing the evolution of the microstructure based on the elementary processes on the dislocation level. The focus of the present paper is on deformation at room temperature or 0.11 Tm. EBSD on single crystals after one pass of ECAP revealed mesoscopic, crystallographically aligned deformation bands resulting from early primary slip avalanches as well as microscopic, crystallographically aligned bands delimited by dense dislocation walls. The bands exhibit a less pronounced substructure evolution than the matrix. TEM confirmed a pole mechanism at superjogs as an essential dislocation multiplication and slip transfer mechanism, but also suggested dislocation reactions allowing combined slip in <200> directions. A model for dislocation generation and slip transfer through the pole mechanism allows estimating the shear realized in the bands.

ISBN:978-87-550-3776-2

Jaar van publicatie:2009

BOF-keylabel:ja

IOF-keylabel:ja

Authors from:Higher Education

Toegankelijkheid:Closed