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Characterization of aging behavior of precipitates and dislocations in copper-based alloys

Published online by Cambridge University Press:  29 February 2012

Shigeo Sato*
Affiliation:
Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai, Miyagi, Japan
Yohei Takahashi
Affiliation:
Research Department, Nissan ARC, Ltd., 1 Natsushima, Yokosuka, Japan
Kazuaki Wagatsuma
Affiliation:
Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Sendai, Miyagi, Japan
Shigeru Suzuki
Affiliation:
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-Po1 Katahira, Sendai, Miyagi, Japan
*
a)Electronic mail: [email protected]

Abstract

The growth of precipitates in a deformed Cu–Ni–Si alloy with an aging treatment and the rearrangement of dislocations were investigated using small-angle X-ray scattering method and XRD line-profile analysis. The small-angle X-ray scattering method was used for characterizing the growth behavior of the precipitates. The results showed that the precipitates grew gradually to a few nanometers in radius when aged under the condition that the alloy exhibited a maximum of the hardness due to precipitation hardening. The growth rate rose from the onset of the overaging, where the hardness started to decrease. The line-profile analysis of copper-based alloy diffraction peaks using modified Williamson–Hall and modified Warren–Averbach procedures yielded a variation in the dislocation densities of the alloy as a function of the aging time. The dislocation density of the alloy before the aging treatment was estimated to be 1.7×1015 m−2 and its high value was held up to the peak-aging time. With the onset of the overaging, however, the dislocation density distinctly decreased by about 1 order of magnitude indicating that a large amount of the dislocations rearranged to release the alloy from the high dislocation-density state. The results suggest that the massive rearrangement of dislocations was accompanied with coarsening of the precipitates.

Type
Technical Articles
Copyright
Copyright © Cambridge University Press 2010

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