抄録
Extended dislocation nodes in αCu–Al solid solution were observed by a transmission electron microscope, and the stacking fault energy (SFE) was determined. The specimens were annealed at 700°C after deformation to eliminate the effect of solute impedance force pinning partial dislocations. First, the variation in SFE with composition was measured and compared with Howie and Swann’s data. It appears that differences between their values and ours are due to the solute impedance stress. The SFE in pure copper was also estimated as 46.4±2.7 erg/cm2 using Liu and Gallagher’s relation. Secondly, the experiments were performed with Cu-15.9 at% Al quenched from different temperatures to study the effect of short range order (SRO) on the SFE. The SFE varies with the quenching temperature, and the results show a good correspondence with those of the electrical resistivity, hardness and specific heat measurements. The variation in SFE with the quenching temperature may be interpreted as being due to SRO rather than quenching stresses. The experiments suggest that SRO is not only responsible for the frictional effects as suggested by many workers, but also might affect the true SFE. The SFE decreases with development of SRO in the sample where stacking faults already exist. This effect of SRO is in the opposite sense to that found when the stacking faults are introduced to an ordered alloy.
