Deformation of LaNi5 by uniaxial compression and hydrogenation

Dislocation structures in LaNi5 after hydrogenation and uniaxial compression have been investigated by transmission electron microscopy. Numerous dislocations are introduced in LaNi5 in the first hydrogen absorption cycle. The majority of them are a-type edge dislocations with Burgers vectors of the 1/3[11 (2) over bar0] types. These a-type edge dislocations introduced during the first absorption cycle seem to be misfit dislocations formed at interfaces between the LaNi5 matrix and hydride, since the result from uniaxial compression deformation indicates that the easiest slip system is slip on {1 (1) over bar 00}[0001], which operates only above 800 degreesC and that a-type dislocations cannot move so easily in response to uniaxial mechanical stresses. Based on the results obtained. the roles of dislocations in the hydrogenation behavior as well as the relationship between the ductility of materials and the reproducibility of hydrogenation characteristics are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.