In situ study of microstructure and strength of severely predeformed pure Cu in deformation at 573 K

0450747 - ÚFM 2016 RIV GB eng J - Journal Article
Blum, W. - Dvořák, Jiří - Král, Petr - Petrenec, M. - Eisenlohr, P. - Sklenička, Václav
In situ study of microstructure and strength of severely predeformed pure Cu in deformation at 573 K.
Philosophical Magazine. Roč. 95, č. 33 (2015), s. 3696-3711. ISSN 1478-6435. E-ISSN 1478-6443
R&D Projects: GA ČR(CZ) GAP108/11/2260; GA MŠMT(CZ) ED1.1.00/02.0068
Institutional support: RVO:68081723
Keywords : ECAP * dynamic recovery * static recrystallization * dynamic recrystallization * grains * in situ observation * strength * stress relaxation
Subject RIV: JJ - Other Materials
Impact factor: 1.632, year: 2015

The influence of grain refinement on the strength of pure Cu at the elevated temperature of 573K was studied in situ in a SEM. Thermomechanical processing by eight passes of equal channel angular pressing at ambient temperature and annealing at test temperature generates grains of 3 μm size. During deformation in the SEM, further grain coarsening occurs by discontinuous recrystallization in subsequent waves causing oscillations of flow stress. Cracks start to form at the boundaries, but partly become intragranular when boundaries move away. The relaxation of flow stress in the periods, where the imposed elongation was interrupted, yields information about the deformation kinetics. Two mechanisms are identified. One is thermally activated glide related with defect generation. The second one accompanies the processes of microstructure restoration. Under the present deformation conditions the grain coarsening by DRX does not soften the material, but leads to slight hardening as high-angle boundaries are exchanged for low-angle boundaries. This is discussed in terms of boundary-mediated processes.
Permanent Link: http://hdl.handle.net/11104/0251981