The change in the shape of gold–copper alloy samples during a disorder $\to$ order phase transformation

The changes in the linear dimensions of ZlM-80 gold–copper alloy samples (with a gold content of 80 wt.%) during atomic ordering are studied. The initial disordered state in some of the alloy samples is formed by quenching from a high temperature, and other samples are disordered as a result of severe plastic deformation. It is found that the change in the shape of specimens with heating strongly depends on their initial state: the ordering causes a decrease in the length of hardened wire specimens, while the length of initially deformed specimens increases. It is shown that the atomic ordering processes give rise, regardless of the initial state, to a decrease in the volume of the alloy under study. The obtained results are of both scientific and practical interest.