Nb双晶中晶界腐蚀与位向差的关系

CORRELATION BETWEEN GRAIN BOUNDARY CORROSION AND MISORIENTATION IN Nb BICRYSTALS

用干涉显微镜研究了具有对称倾斜晶界的Nb双晶的晶界腐蚀。除了在靠近重合位置点阵(CSL)晶界处出现极小值外,腐蚀深度d是随位向差θ的增大而增加的。对小角度晶界,d随θ的变化遵循Read—Shockley关系。用计算机模拟方法计算了晶界的原子结构及其局部膨胀,用自由体积的变化解释了晶界腐蚀的结构依赖性。

Grain boundary corrosion of oriented Nb bicrystals with symmetric tilt boundaries has been investigated by use of interference microscope. The corrosion depth, d, increases with misorientation angle, θ, except near some coincidence-site-lattice boundaries where minimum cusps appear. For small-angle boundaries, d depends on θ following a Read-Shockley type relationship. The atomistic structure and the local expansion of grain boundaries were calculated using a computer simulation method. The structure dependence of grain boundary corrosion is explained in terms of variation in free volume.