Role of Oriented Stress Fields in Two-Way Shape-Memory Alloys

An Overview of Applications of the Mesomechanical Approach to Shape Memory Phenomena — Completed by a New Application to Two-way Shape Memory

“…T2. Training by constrained aging that can be performed in the austenite or martensite state (Kainuma et al, 1986;Zhang et al, 2001). T3.…”

“…One factor that surely plays its role is the changing internal stress-state. In a number of papers this factor is discussed from different points of view (Solovyev and Khatchin, 1974;Christian, 1982;Goldstein et al, 1987;Patoor et al, 1991;Falk, 1993;Zhang et al, 1997;Kafka and Vokoun, 1998;Zhang et al, 2001). Nonetheless, this factor does not seem to be sufficient for a full elucidation of this phenomenon if the effect of the secondary prestrain is not taken into account.…”

“…The region of training TWSM is assumed to be the secondary prestrain, the tertiary prestrain has a quite opposite effect. According to some authors, the physical background of the effect of the secondary prestrain on TWSM is creation of defects and dislocations and fixation of the oriented microstresses (Contardo, 1988;Tadaki et al, 1988;Guilemany and Fernandez, 1995;De Araujo, 1999;Lexcellent et al, 2000;Zhang et al, 2001). In the mesomechanical model, this effect is represented by an increase of the elastic limit c n of the elastic-plastic constituent (constituent of Ni-Ni pairs in a NiTi alloy) due to these factors.…”

Constitutive modeling for the training process of two-way shape memory effect under thermal cyclic loading

“…Generally, the recovery due to two-way SME is less than that of one-way SME. In the literature, different types of training are proposed to induce the two-way shape memory effect: the pseudoelastic cycle (Perkins, 1981), one-way shape memory cycle (Gallardo Fuentes et al, 2002), a combination of one-way and pseudoelastic cycles (Gallardo Fuentes et al, 2002; Tokuda et al, 2001), a constant temperature cycle of transformed martensite (Gallardo Fuentes et al, 2002), secondary deformation in martensite phase (Gallardo Fuentes et al, 2002; Ponikarova et al, 2019) and constrained aging in austenite or martensite phase (Zhang et al, 2002).…”