Grain boundary formation stages in a deformed yellow gold single crystal studied by mechanical spectroscopy

A monocrystalline 18-carat yellow gold sample is deformed stepwise from 2% to 12% at room temperature. The mechanical loss spectrum is recorded and analysed. At low deformations the exponential high temperature background increases. At a critical deformation of 8% an intermediate temperature peak appears. Such peak typical of polycrystals is related to grain boundary sliding. The comparison of a polycrystal formed of low angle grain boundaries (LAGB) only, and samples deformed between 2% and 8% evidence the existence of an intermediate stage. The high temperature peak P3 characterizes the mobility of LAGB that is controlled by the movement of dislocations. (C) 2012 Elsevier B.V. All rights reserved.