The observation of discontinuous precipitation in silver-copper alloys goes back to C. S. Smith. Other elements may also give rise to grain-boundary embrittlement, but copper precipitation at the grain boundaries may lead to enhanced corrosion when the alloy starts to go.....these copper precipitates sometimes take the form of small platelets and the spacing of these may possibly be related to ageing.....it has been difficult to get further than this in terms of dating silver by discontinuous preciptation of copper, but many old silver alloys with about 1.5% - 5% copper content show the characteristic "jig-saw" grain pattern on etching with meandering grain outlines. This has been published by Schweizer and Meyers many years ago.....D
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