Abstract
The behaviour of interdiffusion and layer growth of β and β′ phases in the Cu-Zn system was investigated in the temperature range of 325 to 651°C, and the effect of the order-disorder transformation upon the diffusion behaviour in this alloy was also studied.
The rate of the layer growth and the interdiffusion coefficient of this alloy were influenced by the order-disorder transformation and both values were remarkably reduced at the temperature of transformation.
The interdiffusion coefficient increased monotonically with the increase of Zn concentration in both phases of β and β′. The activation energy for interdiffusion increased in the β′ phase while the value decreased in β phase with the increase of Zn concentration. The activation energy for interdiffusion in the ordered β′ phase was about 1.5 times higher than that in the disordered β phase.
The intrinsic diffusion coefficient of Zn atom showed the value of about 2 times higher than that of Cu atom in the disordered phase, while these two factors were nearly coincided with each other in the ordered phase.
It was shown from the measurement of the Kirkendall effect that the diffusion was controlled by a vacancy mechanism in the disordered phase and by the six atoms-vacancy jump mechanism in the ordered phase.
