Effect of heat treatment on diffusion, internal friction, microstructure and mechanical properties of ultra-fine-grained nickel severely deformed by equal-channel angular pressing

Severe plastic deformation via equal-channel angular pressing was shown to induce characteristic ultra-fast diffusion paths in Ni (Divinski et al., 2011). The effect of heat treatment on these paths, which were found to be represented by deformation-modified general high-angle grain boundaries (GBs)...

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Bibliographic Details
Published in:Acta materialia 2015-01, Vol.82, p.11-21
Main Authors: Divinski, Sergiy V., Reglitz, Gerrit, Golovin, Igor S., Peterlechner, Martin, Lapovok, Rimma, Estrin, Yuri, Wilde, Gerhard
Format: Article
Language:English
Subjects:
Deformation effects
Deformation mechanisms
Diffusion
ECAP
Equal channel angular pressing
Grain boundary diffusion
Heat treatment
Internal friction
Microhardness
Microstructure
Nickel
SPD
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Summary:Severe plastic deformation via equal-channel angular pressing was shown to induce characteristic ultra-fast diffusion paths in Ni (Divinski et al., 2011). The effect of heat treatment on these paths, which were found to be represented by deformation-modified general high-angle grain boundaries (GBs), is investigated by accurate radiotracer self-diffusion measurements applying the 63Ni isotope. Redistribution of free volume and segregation of residual impurities caused by the heat treatment triggers relaxation of the diffusion paths. A correlation between the GB diffusion kinetics, internal friction, microstructure evolution and microhardness changes is established and analyzed in detail. A phenomenological model of diffusion enhancement in deformation-modified GBs is proposed.
ISSN:1359-6454
1873-2453
DOI:10.1016/j.actamat.2014.08.064