C-type dislocations emitted from cracks introduced in a thin foil of LaNi5

The nature of dislocations emitted from cracks introduced in a thin foil of LaNi5 has been characterized by means of transmission electron microscopy. Dislocations emitted from cracks are determined to be of the c-type (b (Burgers vector)=[0001]) moving on {10 (1) over bar 0} prism planes. Although grown-in dislocations of the a-type (b=1/3[11 (2) over bar 0]) locate near cracks where the emission of c-type dislocations occurred, these a-type dislocations are not observed in motion, indicating the difficulty in the motion of a-type dislocations. The implications of these results for controlling the extent of cracking during cycles of hydriding-dehydriding of alloys based on LaNi5 are discussed. (C) 1998 Elsevier Science S.A.