The Interior of the Pseudoelastic Hysteresis

An interesting problem within the research on shape memory is provided by the investigation of the pseudo-elastic hysteresis loop that accompanies the strain-induced austenitic-martensitic phase transition. Miller [1] suggested by thermodynamic arguments that the size of that loop should be related to the coherency energy at interfaces between martensite and austenite. That proposition received a boost when Müller & Xu [2] showed that the same thermodynamic arguments predicted the onset of internal yield and recovery inside the hysteresis loop on a well-definqd line of unstable phase equilibrium. Recently Fu, Müller and Xu [3] have reported results with improved specimens and methods of observation that may help to understand the nature of metastability inside the hysteresis loop.