Stress-Ordering Effect on Thermal Expansion of CuAu Single Crystals

Abstract

Linear thermal expansion of CuAu single crystals was measured. When a bar-formed specimen was slowly cooled from above the transition temperature under compressive stress along its longitudinal direction, it was confirmed that the c-axes of the ordered phase were predominantly lined up in one of the cubic axes nearest to the stress direction. Furthermore a linear relationship was established to hold between the compressive stress previously applied and the amount of the dilatometric change due to the order-disorder transition. However, even when some of the crystals were initially annealed free from external stress, the tetragonal c-axes were not distributed statistically along the three original cubic axes.