The influence of texture on the shape-memory effect in polycrystals

A model is developed to show that texture is a crucial factor in determining the shape-memory effect in polycrystals. In particular, it is established that texture is the reason why the strains recoverable in Ti-Ni are so much larger than those in Cu-based shape-memory alloys in rolled, extruded and drawn specimens. Further, it is shown that both these materials recover relatively small strains in sputter-deposited thin films due to unfavorable texture. It is found that even the qualitative behavior of combined tension-torsion can critically depend on the texture. The results are in good agreement with experimental observations. Finally, textures are suggested for improved shape-memory effect. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.