Changes in the shape of wires of Cu-Au alloys in longitudinal and transverse directions induced by disorder-order (A1-L10) transition

A dilatometric study of wire samples of Cu-50at.%Au and Cu-56at.%Au alloys was carried out. A feature of this work is the measurement of the temperature coefficient of linear expansion in two directions simultaneously: longitudinal and transverse ones. It has been revealed that the atomic ordering by L10 type leads to a slight decrease in all the sizes of the initially quenched samples. However, the pre-deformed samples become longer at the ordering and simultaneously decrease in their cross-sections. It was concluded that the residual stresses in the deformed sample caused a predominant orientation of the tetragonal c-domains during the phase transition. The obtained results allowed drawing and comparing the temperature dependences of the change in the volume of alloys during heating. It is shown that the restructuring of the structure in both alloys occurs in similar temperature intervals, but with different kinetics.