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Библиогр.: 34 назв.

Abstract. In this study, we investigated the effect of the number of Ti3Ni4 particle variants (obtained via stress-free and stress-assisted aging at 823 K for 1 hour) on the shape memory effect, superelasticity, and strength properties of the B2-phase in high-nickel [001]-oriented Ti-51.5 at.% Ni single crystals. Four crystallographically equivalent variants of lenticular Ti3Ni4 particle with the {111}B2 habit plane and a diameter of 250–300 nm were obtained via stress-free aging. Aged under an applied compressive stress of 150 MPa along the <111> direction, single crystals contain predominantly one variant of Ti3Ni4 particle, forming plane-parallel plates with lengths from 1 to 5 μm. The oriented arrangement of semi-coherent Ti3Ni4 particles leads to the formation of long-range stress fields, an increase of 23 K in the martensitic transformation (MT) starting temperature Ms, the induction of a two-way shape memory effect, and a decrease of 200 MPa in the stress required to obtain the maximum reversible strain (1.5–1.7%) during cooling/heating cycles compared to stress-free aged single crystals. The number of variants of Ti3Ni4 particle determines the mechanism of the formation of B19'-martensite and the strength properties of the B2-phase (1600 MPa in stress-assisted aged crystals and 2100 MPa in stress-free aged crystals).