Thermal expansion of the Ag₃Mg alloy in the ordered and disordered states

The α phase of the silver–magnesium alloy system containing 26.1 atomic per cent magnesium has been studied by X-ray diffraction methods in the temperature range from 20 to 678°C. The tetragonal symmetry of the low-temperature phase is confirmed. The temperature variation of the lattice parameters and the volume expansion coefficient have been determined. It seems likely that the order–disorder transformation is a first-order rather than a second-order transformation.