An analysis of the influence of heat treatment on the features of variation in parameters of multiple shapememory effect for porous titanium nickel produced by the method of self propagating high-temperature synthesis (SHS) is presented. It is shown that heat treatment of porous titanium nickel substantially affects its structure and physicomechanical properties. Annealing at the temperatures within Т = 400-600°C favors an improvement of its physicomechanical characteristics and manifestation of the maximum shape memory effect. It is revealed that a further increase in the temperature, however, results in deterioration of its properties. An optimal temperature of heat treatment of articles made from pore-permeable titanium nickel is proposed -Т = 400-450°C for 1 hour in vacuum.

The temperature dependences of electrical resistivity through the region of martensitic transformations in the alloys based on titanium nickelide are shown to exhibit pronounced asymmetry under conditions of direct and reverse transformations. It is assumed that this behavior is due to different character of temperature dependences of electrical resistivity in the austenite and martensite phases, which provide an explanation for this marked asymmetry.Phase transitions in the alloys based on titanium nickelide cover a wide range of martensitic transformations such as: В2-В19, В2-В19′, В2-R-B19′, B2-B19′′, etc. [1-21]. One of the most useful, reliable and informative methods of determining the temperature intervals and sequences of thermoelastic martensitic transformations (MTs) in the TiNialloys is the method of obtaining the temperature dependences of electrical resistivity. It should be noted that there are a number of phenomena accompanying MTs, which complicate calculation of the characteristic transformation temperatures in these alloys. They manifest themselves in the asymmetry of variations in the temperature dependences of electrical resistivity ρ(t) during the direct B2→R→B19′ and reverse B19′→R→B2 martensitic transformations (Fig. 1).The MT temperatures in these alloys are measured by a number of different methods that, presumably, should give similar results. In fact, the MT temperatures obtained by different methods are different [2,5]. Among the techniques frequently used are the calorimetric measurements and the measurements of electrical resistivity. These are often employed to determine the MT temperature intervals and sequences [2,6,7]. Moreover, there are singularities in the temperature dependences, which considerably complicate the derivation of the characteristic temperatures of the reverse MT in the alloys in question. These singularities are associated with the fact that MTs are accompanied by the processes differing in their nature, which are manifested in different temperature intervals in the course of rearrangement of the crystal lattice. The fact that an MT is a complicated sequence of different processes is well exhibited during thermal cycling through the MT region; this gives rise to evolution of the curves of electrical resistivity (Fig. 1). In particular, in the Ti(Ni, Mo, V) alloys with a low content of vanadium, the dependences ρ(t) indicate only the B2→ B19′ MT. Thermal cycling, on the other hand, results in a more complicated sequence of MTs: B2→R→B19′, which is clearly observed in the temperature dependences of electical resistivity presented in Fig. 1. In addition, the character of electrical resistivity changes also varies with concentration of the components, with a strong variation of the dependences ρ(t) with the number of the thermal cycles through the MT region. Earlier it was shown [1,2,[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]