THE INFLUENCE OF TEXTURE ON THE SHAPE-MEMORY EFFECT IN POLYCRYSTALS

A model is developed to show that texture is a crucial factor in deter mining the shape-memory effect in polycrystals. In particular, it is e stablished that texture is the reason why the strains recoverable in T i-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 t hese materials recover relatively small strains in sputter-deposited t hin films due to unfavorable texture. It is found that even the qualit ative behavior of combined tension-torsion can critically depend on th e texture. The results are in good agreement with experimental observa tions. Finally, textures are suggested for improved shape-memory effec t. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.