901 TiNi 形状記憶合金の変形特性

Abstract

The basic deformation properties of pseudoelasticity and shape memory effect due to martensitic transformation and R-phase transformation were investigated experimentally for TiNi shape memory alloy (SMA) wire subjected to various maximum strain. The properties of transformation temperature were discussed based on differential scanning calorimetry. The main results were summarized as follows. (1) The deformation properties of pseudoelasticity and shape memory effect were determined based on a stress-temperature phase diagram in which stress and temperature were variables. The stress-temperature phase diagram was useful for design of SMA elements. (2) If maximum strain was in the martensitic transformation region, both reverse transformation stress and reverse transformation temperature were almost constant. If maximum strain was in the upswing region after completion of the martensitic transformation, reverse transformation stress decreased and reverse transformation temperature increased with an increase in maximum strain, resulting in movement of the reverse transformation lines downward and to the right.