Recrystallization kinetics in copper: Comparison between techniques

High-purity polycrystalline nickel (99.99 pct purity) was cold rolled to equivalent von Mises strains from 1.4 to 4.5 (70 to 98 pct reduction in thickness). The stored energy of the deformed samples was measured using both microstructural parameters obtained from transmission electron microscope (TEM) investigations and differential scanning calorimetry (DSC). For the microstructure-based estimate of the stored energy, the required parameters are the misorientation angles across, and the spacings between the dislocation boundaries and high-angle boundaries present after deformation. It was found that the stored energy determined from both TEM and DSC investigations increased linearly with strain, with the latter being larger by a factor of between 1.9 and 2.7. This difference can be reduced by considering the contribution to the stored energy from other sources.

Section: B Stored Energy-temmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stored Energy in Nickel Cold Rolled to Large Strains, Measured by Calorimetry and Evaluated from the Microstructure

Knudsen

Cao

Godfrey

et al. 2008

“…[8] Grain-scale stored energy data has been obtained using either X-ray or neutron diffraction methods based on an analysis of peak broadening. [9,10] In order to obtain information on the local scale, only methods based on an investigation of the microstructure are applicable.…”

Section: Introductionmentioning

confidence: 99%

Microstructural-Based Measurement of Local Stored Energy Variations in Deformed Metals

Godfrey

Hansen

Jensen

2007

Three single crystals of typical fcc rolling texture orientations-{112}<111> (C), {123}<634> (S), and {110}<112> (B)-have been deformed by plane strain compression at room temperature, and the stored energy of deformation in each has been calculated from measurements in the transmission electron microscope (TEM) of dislocation boundary spacings and misorientation angles. The stored energy has been determined on two length scales: the single crystal scale and, for orientations in which localized glide bands (LGBs) are present, on the local length scale. On the crystal scale, it is found that the stored energy shows a strong dependence on the crystallographic orientation; the highest is for the C orientation and the lowest is for the B orientation. For the C and S orientations, where LGBs develop during deformation, the differences in stored energy between the LGB and matrix regions can be as large as the differences between the average values for each single crystal. The observed variation of stored energy on the crystal scale and the local scale can be related to the experimental observations of the flow stress and to the recrystallization behavior of the three crystal orientations.

“…In a very recent investigation, Woldt and Juul Jensen [14] compared various techniques for measuring the isothermal recrystallization kinetics of cold-rolled copper at 121 ЊC. Calorimetry was among the techniques employed.…”

Section: Introductionmentioning

confidence: 99%

Grain boundary mobility during recrystallization of copper

Vandermeer

Jensen

Woldt

1997

Self Cite

Average grain boundary migration rates during recrystallization of cold-deformed copper were estimated from stereological measurements. In the same material, the instantaneous driving forces for boundary migration during recrystallization were calculated from calorimetric measurements of the release of the stored energy of cold work. The migration rate dependence on driving force was analyzed in the context of grain boundary migration rate theory, and within experimental error, a linear dependence was observed. The average mobility of grain boundaries migrating during recrystallization of cold-worked copper at 121 ЊC was calculated to be 6.31 ϫ 10 Ϫ10 (m 4 s Ϫ1 MJ Ϫ1 ). This result was found to be consistent with single boundary, curvature-driven grain boundary mobilities measured in copper at higher temperatures. It was also demonstrated that the average grain boundary mobility was reasonably within the expectation (order of magnitude uncertainty) of the Turnbull single process model of boundary migration with a process akin to grain boundary self-diffusivity as the rate-controlling atomic mechanism.