ABSTRACT
The feature of [100](010) dislocation motion in the pre-multiplication region in white tin was investigated by means of an etch hillock technique. In the cource of dislocation motion, some stopped on the way and did not move again, but others moved again after a standstill for a time. The first free path (FFP) of the dislocation to encounter an obstacle was measured, and its distribution was represented in a histogram. The form of this histogram was interpreted statistically on the basis of the assumption that point obstacles were scattered randomly on a slip plane. The result of calculation represented an adequate correlation between the obstacle density and the dislocation density counted on the surface. The obtained value of the critical breaking angle of dislocation suggested that the strength of obstacles would be rather weak. From these results, it was inferred that effective obstacles for individual dislocation motion are forest dislocations of secondary slip systems.
