Measurement of elastic constants of monoclinic nickel-titanium and validation of first principles calculations

Polycrystalline, monoclinic nickel-titanium specimens were subjected to tensile and compressive deformations while neutron diffraction spectra were recorded in situ. Using these data, orientation-specific and macroscopic Young's moduli are determined from analysis of linear-elastic deformation exhibited by 13 unique orientations of monoclinic lattices and their relationships to each macroscopic stress and strain. Five of 13 elastic compliance constants are also identified: s(11) = 1.15, s(15) = -1.10, s(22) = 1.34, s(33) = 1.06, s(35) = -1.54, all x 10(-2) GPa(-1). Through these results, recent atomistic calculations of monoclinic nickel-titanium elastic constants are validated. (C) 2013 AIP Publishing LLC.