Controlled initiation and propagation of stress-induced martensitic transformation in functionally graded NiTi

Martensitic Transformation of NiTi and NiTi- TiC Composites

The role of intergranular constraint on the stress-induced martensitic transformation in textured polycrystalline NiTi

The in ̄uences of grain boundaries and relative grain misorientations on stress-induced martensitic transformations in NiTi are studied using unique experiments and ®nite element modeling. Tensile and compressive mechanical tests reveal that polycrystalline NiTi with a dominant <111> ®ber texture and single crystal NiTi oriented along the [111] direction exhibit nearly identical stress±strain cu...

Functionally graded NiTi shape memory alloys

In this study, in order to obtain a functionally graded material, NiTi strips were annealed at 350°C, 450°C and 550°C in a furnace using an assembly that allowed a temperature gradient along them, and their transformation temperatures were studied by Differential Scanning Calorimetry (DSC). Furthermore, the strips were bent at both ends and dipped into a water bath at room temperature which was...

Stress-induced martensitic transformations in NiTi and NiTi–TiC composites investigated by neutron diffraction

Superelastic NiTi (51.0 at.% Ni) specimens reinforced with 0, 10 and 20 vol.% TiC particles were deformed under uniaxial compression while neutron diffraction spectra were collected. The experiments yielded in-situ measurements of the thermoelastic stress-induced transformation. The evolution of austenite/martensite phase fractions and of elastic strains in the reinforcing TiC particles and the...

Energy landscape for martensitic phase transformation in shape memory NiTi

First-principles calculations are presented for parent B2 phase and martensitic B19 and B190 phases in NiTi. The results indicate that both B19 and B190 are energetically more stable than the parent B2 phase. By means of ab initio density functional theory, the complete distortion–shuffle energy landscape associated with B2? B19 transformation in NiTi is then determined. In addition to accounti...