ON THE FULL-FIELD DEFORMATION OF SINGLE-CRYSTAL CUALNI SHAPE-MEMORY ALLOYS - STRESS-INDUCED BETA(1)-]GAMMA'(1) MARTENSITIC-TRANSFORMATION

Using high sensitivity Moire interference technology, the full deforma tion fields about the stress-induced martensitic transformation beta(1 ) --> gamma'(1) of single crystal CuAlNi shape memory alloys (SMAs) ar e obtained. A straight and sharp interface between martensite and pare nt phases and its motion during transformation process are clearly obs erved. The elastic anisotropic properties of the crystal are also quan titatively characterized by this technique. The results show that ther e is no deformation incompatibility between the two phases, which is d ifferent from that of pseudoelasticity where another stress-induced ma rtensitic transformation beta(1) --> beta'(1) occurs. The present resu lts provide an accurate experimental solution for the phase transforma tion problem in solids.