Cu単結晶(111)面の280 Kにおける丸川液腐食によるらせん転位位置の溶解速度

Abstract

The dissolution process of (111) faces of Cu crystals in Marukawa’s solution (FeCl3·6H2O 0.88 kmol·m−3, HCl 4.4 kmol·m−3, HBr 0.12 kmol·m−3) was studied. The etching was carried out at 280 K for 10-50 s, and the three-dimensional size of etch pits revealed at screw dislocations and the dissolved thickness of the matrix surface were measured by replica electron microscopy and two-beam interferometry, respectively.After an initial lapse of 10 s, the width and depth of dislocation etch pits increased linearly with the etching time, while the side slope of etch pits decreased slowly and approached a constant value of 0.1. The dissolved thickness of the matrix surface increased also linearly with the etching time. From the growth rate of etch pits and the removal rate of the matrix surface, the vertical dissolution rate along the dislocation line, vd, and the lateral one, vh, were determined. Using these values, it has been estimated from the spiral theory of crystal dissolution at a screw dislocation site that the spacing of a spiral step is ∼2.1×10−3 μm and that the radius of curvature at a spiral center, which is equal to the size of critical nucleus for two-dimensional nucleation on a stress-free surface, is 1.1×10−4-5.3×10−4 μm. From the nucleation theory of matrix surface dissolution, the rate of two-dimensional nucleation on the dislocation-free surface has been deduced to be 4.3×105 μm−2·s−1.