ETCHING PHENOMENA IN THE [111] PLANE OF NIOBIUM.

For single‐ and polycrystalline niobium the relation between etch figures and dislocations is qualitatively demonstrated. Repeated etching allows investigation of the movement and multiplication of dislocations. Besides triangular etch hillocks there often occur etch traces or walls, respectively, and networks that may be interpreted as dislocations lying nearly parallel to the observation plane. Etch figures of helical dislocations have been found too.