Temperature Dependent Stress–Strain Behavior and Martensite Stabilization in Magnetic Shape Memory Ni51.1Fe16.4Ga26.3Co6.2 Single Crystal

Direct observation of hierarchical nucleation of martensite and size-dependent superelasticity in shape memory alloys.

Martensitic transformation usually creates hierarchical internal structures beyond mere change of the atomic crystal structure. Multi-stage nucleation is thus required, where nucleation (level-1) of the underlying atomic crystal lattice does not have to be immediately followed by the nucleation of higher-order superstructures (level-2 and above), such as polysynthetic laths. Using in situ trans...

Shape memory and ferromagnetic shape memory effects in single-crystal Ni2MnGa thin films

Stabilisation of Martensite in Copper Based Shape Memory Alloys

The experimental facts on the stabilisation of martensite in copper base shape memory alloys, of interest to the scientific investigator and the practical alloy processor and user are reported. Factors that have an influence on stabilisation are considered in this respect. The mechanisms proposed in the literature to explain stabilisation are critically examined.

Magnetization changes in Ni–Mn–Ga magnetic shape memory single crystal during compressive stress reorientation

Magnetization as a function of strain of a Ni48.5Mn30.8Ga20.7 single crystal during 9 MPa compressive loading test was obtained by means of vibrating coil magnetometry for different static magnetic fields up to 1.15 T. The dependency is monotonic, nonlinear and shows a small hysteresis. Maximum reversible change of magnetization is 30% for a 0.6 T field, and irreversible change of about 50% is ...

On the mechanical behavior of single crystal NiTi shape memory alloys and related polycrystalline phenomenon

Room temperature monotonic and cyclic stress–strain curves for single crystal and polycrystalline NiTi shape memory alloys containing Ti3Ni4 precipitates are presented. The tensile and compressive single crystal results illustrate the importance of crystallographic texture, the unidirectional nature of the martensitic transformation, and martensite detwinning on tension-compression stress–strai...