Influence of thermo-mechanical processing on ordering kinetics in 18 karat red gold alloy

The aim of this project is to understand the correlation between alloy composition and the build-up of internal stresses in 18 carat Au-Ag-Cu alloys under thermo-mechanical loads. The copper rich end of this ternary system exhibits order-hardening of the equiatomic AuCu phase. There is very limited information in literature on the ordering transformation behavior of the copper-rich alloys under anisothermal annealing and in a pre-deformed state; and more importantly, how does the misfit strain induced by ordered nano- precipitates affect internal stresses of the material. The link between microstructural evolution and residual stresses is lacking. This project aims to quantify the coupling between the morphology of ordered precipitates and the evolution of residual stresses in pre-deformed samples, via in-situ temperature experiments with synchrotron x-ray and neutron diffraction and scattering methods. Electron microscopy will complement the microstructural investigations. This study will shed light on how thermo-mechanical loads impact internal stresses on 18 carat Au-Ag-Cu alloys subject to order-hardening of equiatomic AuCu.