Diffusion of ⁶⁵Zn in Aluminum and Al–Zn–Mg Alloy over a Wide Range of Temperature

Abstract

The diffusivities of Zn in Al and Al-5 wt% Zn-2 wt% Mg alloy were determined by the residual-activity method with radioactive tracer ⁶⁵Zn in the temperature ranges of 165∼645°C and 165∼560°C, respectively.
The temperature dependences of the diffusivities of Zn in Al and its alloy are given by the following equations:
D_Zn/Al=(0.177_−0.037^+0.047)exp{−(28.2±0.3)kcal⁄mol⁄RT}cm²⁄sec, and
D_{Zn/Al–Zn–Mg}=(0.682±0.017)exp{−(29.8±0.02)kcal⁄mol⁄RT}cm²⁄sec.
We have evaluated the difference in activation energy (ΔQ) between the impurity diffusion of Zn in Al and the self-diffusion of Al by means of the oscillating potential and Le Claire’ theory. The result shows that the theoretical value of ΔQ agrees well in both sign and order of magnitude with the experimental value.