In situ study of thermally activated flow and dynamic restoration of ultrafine-grained pure Cu at 373 K

0483092 - ÚFM 2018 RIV US eng J - Článek v odborném periodiku
Blum, W. - Král, Petr - Dvořák, Jiří - Petrenec, M. - Eisenlohr, P. - Sklenička, Václav
In situ study of thermally activated flow and dynamic restoration of ultrafine-grained pure Cu at 373 K.
Journal of Materials Research. Roč. 32, č. 24 (2017), s. 4514-4521. ISSN 0884-2914. E-ISSN 2044-5326
Grant CEP: GA MŠMT(CZ) LQ1601
Institucionální podpora: RVO:68081723
Klíčová slova: Cu * dynamic grain coarsening * dynamic recovery * ECAP * in situ * stress relaxation * UFG
Obor OECD: Materials engineering
Impakt faktor: 1.495, rok: 2017

Pure Cu was made ultrafine-grained by equal channel angular pressing on route BC at ambient
temperatures and deformed in situ in a scanning electron microscope at the elevated temperature
of 373 K and at a constant total strain rate of 10-4 s-1. Deformation was repetitively stopped to
take micrographs of the grain structure on the same area of observation, revealing limited activity
of discontinuous dynamic recrystallization. During the stops of deformation, the flow stress was
relaxing. The relaxation of stress as function of time was used to determine the rate of inelastic
deformation as a function of stress, from which the activation volume V of the thermally
activated flow was derived. It is found that the normalized values of V were lying in the same
order generally found for coarse-grained pure materials. This seems to be in conflict with the
literature. However, the conflict is resolved by noting that the literature results refer to quasistationary
deformation with the concurrent dynamic recovery in contrast to the present results
obtained at a virtually constant microstructure. The interpretation of the two kinds of activation
volumes for thermally activated flow is discussed.
Trvalý link: http://hdl.handle.net/11104/0279782