On Deformation of A-M Interface in Single Crystal Shape Memory Alloys and Some Related Issues

Recent experimental results on the deformation field of single crystal CuNiAl shape memory alloys (SMA) by using Moire´ interference technique are reported and two kinds of austenite-martensite (A-M) interfaces with different deformation features are identified. The experimental discovery questioned the invariant plane hypothesis used in crystallographic theory of martensitic transformation. Some fundamental issues on the property of A-M interface and the related micro- and macro-deformation features are discussed.