Structural defects in Ni-Ti alloys in the region of B2-phase homogeneity

A comparison is made of the x-ray and pycnometric densities of Ti-Ni alloys, with a high nickel content relative to the equiatomic composition, when the alloys are quenched outside the region of β-phase homogeneity. An analysis is made of the possibility of the formation of vacancies, interstitial atoms, triple defects, and substitutional defects in the alloys. It is concluded that substitutional defects are formed: nickel atoms which are ″excess″ atoms relative to those found at the lattice points in the CsCl superstructure are located in the titanium sublattice. An evaluation showed that in the formation of alloys near the equiatomic composition of TiNi, the atomic volumes of titanium and nickel are about 1.8 and 7.4% smaller than for the pure components, respectively.