Abstract
The (111) surface of Cu-0.01〜0.2 at% Au alloy crystals was etched for 10s at 280 K in Young's solution (1 kmol・m^<-3> (NH_4)_2S_2O_8> 6kmol・m^<-3> NH_4OH, 0.3 kmol・m^<-3> NH_4Br) using a rotating disc method. The dissolved depth of matrix surface S was measured by twobeam interferometry and the width h and depth d of triangular pyramid of dislocation etch pits were measured by replica electron microscopy. The horizontal dissolved length and the vertical dissolved depth at the dislocation site, Hand D, were determined from S, h and d, respectively. Both H and D increased to a maximum value at Au concentration as small as 0.01-0.05 at% and then decreased gradually, while S increased slightly with a small increase of Au concentration and attained a constant value at 0.03-0.2 at% Au. It was shown that these results could be explained qualitatively on the basis of the two-dimensional nucleation theory of crystal dissolution by considering the variations of the mobility of step, the activation energy for dissolution and the difference of chemical potentials when Au concentration was increased.
