Reconstruction of phase distributions in NiTi helical spring: comparison of diffraction/scattering computed tomography and computational modeling

We successfully reconstructed spatial phase distributions within a cross-section of a stretched NiTi helical spring via x-ray diffraction/scattering computed tomography (DSCT) and compared them with predictions obtained from a finite element simulation; the simulation employed an established phenomenological constitutive model tailored for NiTi shape memory alloys. The comparison corroborated the direct correspondence between the internal variables representing (volume fraction of) phases in the constitutive model and their experimental counterparts. This case study also showed that because of the distinct diffraction contrast between austenite and martensite, DSCT allows visualization of phase gradients within the material.