Recrystallization and Grain Boundary Formation in an 18-Carat Gold Alloy Studied by Mechanical Spectroscopy

Abstract:

Heavily deformed 18-carat yellow gold samples show a recrystallization peak at 700 K during the first heating. The mechanical loss spectrum of polycrystals shows a relaxation peak at about 780 K, which is absent in single crystals made from the same alloy. Stepwise deformation of a single crystal from 2 % to 10 % causes an increase of the high temperature mechanical loss background and the appearance of a high temperature peak. At 8 % deformation the high temperature peak disappears and the peak that is normally observed in polycrystals appears. The increase of the exponential background is interpreted as due to the introduction of new dislocations whereas the high temperature peak is attributed to a relaxation mechanism in the sub grain boundaries. The peak of polycrystalline samples located at intermediate temperatures depends on the grain size: with grain growth, the peak position shifts to higher temperatures. The peak temperature can be related to the mean grain size.

• Periodical: Materials Science Forum (Volume 753)
• Pages: 17-20
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.753.17
• Online since: March 2013
• Authors: Ann Kathrin Maier, Iva Tkalcec-Vaju, Daniele Mari, Robert Schaller
• Keywords: 18-Carat Gold Alloys, Dislocation, Grain Boundary, Internal Friction, Recrystallization

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