The relationship between grain-boundary structure and the diffusivity of zinc along aluminium grain boundaries

The influence of grain-boundary structure on the boundary diffusion of ⁶⁵Zn at 100 and 150°C in coarse-grained pure aluminium was analysed by electron channelling pattern and Auger electron autoradiography. Precise determination of the orientation relationship is achieved by the former, while the boundary segregation of zinc of the order of 0.01% is analysed by the latter technique. Diffusion enhancement was observed in most of the grain boundaries to various degrees; in 40% of the boundary triple points the enhancement in one boundary was less than half of the other two boundaries. One third of such boundaries were small-angle boundaries and the rest were mostly coincidence boundaries.