Microstructural investigation of the annealing behaviour of high-pressure torsion (HPT) deformed copper
Samples of polycrystalline 99.99% Cu were deformed by high-pressure torsion at room temperature and a hydrostatic pressure of about 8 GPa to a shear strain of about 100. After annealing at different temperatures the structural-elements sizes (grain/subgrain, scattering domain) were determined by sca...
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Veröffentlicht in: | Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2007-07, Vol.462 (1), p.139-143 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Samples of polycrystalline 99.99% Cu were deformed by high-pressure torsion at room temperature and a hydrostatic pressure of about 8
GPa to a shear strain of about 100. After annealing at different temperatures the structural-elements sizes (grain/subgrain, scattering domain) were determined by scanning electron microscopy and multiple X-ray Bragg profile analysis. The evolution of the strength of the samples was monitored by microhardness measurements and its relation to the development of the structural-elements sizes has been investigated. The strength turns out to be correlated to the grain size: it decreases when the grain size starts to increase considerably upon annealing at homologous temperatures well above 30% of the melting temperature. Compared with conventional deformation, a very high dislocation density is present in the initial state and after annealing at 0.3
T
m (
T
m – melting temperature) the number of dislocations is reduced considerably. Thus, in the present case, the recovery of dislocations starts at lower homologous temperatures than in conventionally deformed materials. |
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ISSN: | 0921-5093 1873-4936 |
DOI: | 10.1016/j.msea.2005.11.085 |