An X-ray determination of the thermal expansion of silver and copper-base alloys at higher temperatures. III. Ag–Ge and Cu–Ge

X-ray measurements of the lattice spacings in three Ag-Ge alloys in the temperature interval 30-595°C and in two Cu-Ge alloys in the temperature interval 25-611°C, in the solid-solution range, have been made with a Unicam 19 cm high-temperature camera. The measured lattice spacings have been found to increase non-linearly with temperature, this non-linearity being slightly enhanced for Cu-9.25 at.% Ge alloy. The dependence of the measured lattice spacings on temperature has been expressed in an analytical form (polynomial of second degree) from least-squares fitting of the data. The thermal expansion coefficient, α, for the alloys considered, in general, has been found to decrease linearly with increasing temperature (from ∼25 to ∼17 × 10^-6°C^-1), except for the greater germanium concentration (9.25 at.%) in copper solvent where the tendency is reversed.