Strain mapping of crack extension in pseudoelastic NiTi shape memory alloys during static loading

Interatomic potential for the NiTi alloy and its application

“…However, for these phenomena of plastic deformation [8,9], crack [10,11] with a great amount of atoms, ab initio methods restricted to a few hundred atoms or less cannot tackle and largescale atomistic simulations on the basis of a parameterized semiempirical potential are required. Up to now, such kind of empirical potentials for NiTi alloy are lacking because it needs to reproduce physical properties of both austenite and martensite phases very well.…”

In Situ Neutron Diffraction Studies of Large Monotonic Deformations of Superelastic Nitinol

“…There is a gap between these techniques in an ability to study the responses of bulk components whose sample length scales of interest are of several hundred microns to several millimeters. Here, high-energy X-ray powder diffraction provides a solution to study SMA micromechanics with micron resolution in a manner parallel to neutron diffraction, but with finer focus [19][20][21][22][23], while new high-energy diffraction microscopy (HEDM) techniques promise to create new three-dimensional means that allow for simultaneous observations of the individual responses of thousands of individual crystals at once [24,25].…”

Evolution of Intergranular Stresses in a Martensitic and an Austenitic NiTi Wire During Loading–Unloading Tensile Deformation

“…Their study also showed a very small residual strain in the {110} B2 austenite family after super-elastic loading. Using synchrotron X-ray diffraction, Young et al [30] also studied the internal strains in the austenite and the martensite at the crack tip of a pseudo-elastic NiTi alloy. This study showed that strains in austenite became compressive while those in the martensite became more tensile at the onset of SIM transformation in the loading direction.…”

“…The mechanisms of martenite detwinning [4] and stress-induced phase transformation, [5,6] the effect of the microstructures such as phase constitutions, [7,8] grain size, [9,10] precipitates and inclusions, [11][12][13] crystal orientations, [13,14] and deformation conditions [7,8,[14][15][16] on the thermal mechanical behavior and fatigue properties have been studied. New technologies such as in situ EBSD, [17] and in situ neutron and synchrotron X-ray diffractions [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] have recently been used to gain insight into the material behavior at the microscopic level. The evolution of martensite texture during thermal cycling and deformation, [18][19][20] the elastic modulus of the monoclinic martensite, [20][21][22][23][24] the phase transformation and strain partitioning during the stress-induced martensite (SIM) phase transformation, [25] and the micro-mechanical behavior at the crack tip of martenstic …”