Stress-Induced Thermoelastic Martensitic Transformations and Functional Properties in [011]-oriented NiTiHfPd Single Crystals

Thermal and stress-induced martensitic transformations in NiFeGa single crystals under tension and compression

Heat treatment and stress state effects on the martensitic transformation in [001] and [123] oriented single crystal Ni54Fe19Ga27 alloys are determined. Characteristic temperatures increase for longer aging times and higher hold temperatures. The non-aged [001] crystals exhibit the smallest stress hysteresis and lowest critical stress in tension. The experimental results are interpreted based o...

Stability of thermally-induced martensitic transformations in bi-atomic crystals

Some of the most interesting, and technologically important solid–solid transformations are the 1rst order di2usionless transformations that occur in certain equiatomic, ordered, bi-atomic crystals. These displacive transformations include thermally-induced, reversible, proper martensitic transformations as seen in shape memory alloys such as NiTi (where group–subgroup relationships exist betwe...

Simple Model of Hysteresis in Thermoelastic Martensitic Transformations

To attain a better understanding of the hysteretic behaviour in shape memory alloys we present in this work a simple phenomenological model based on the thermoelastic balance that must be fulfilled at every step of transformation. The model is built on the simplest choice for the chemical and non-chemical free energies, that is, a first order dependence of these functions on T and x (transforme...

Stress-free two-way thermoelastic shape memory and field-enhanced strain in Ni52Mn24Ga24 single crystals

Stress-free and two-way thermoelastic shape memory, with 1.2% strain and 6 K temperature hysteresis, has been found in single crystalline Ni52Mn24Ga24 . The deformation can be enhanced more than three times, up to 4.0% shrinkage with a bias field 1.2 T applied along the measurement direction, or changed to 1.5% expansion by the 1.2 T applied perpendicular to the measurement direction. For achie...

Three-dimensional Landau theory for multivariant stress-induced martensitic phase transformations. II. Multivariant phase transformations and stress space analysis