The main requirement to the active elements of communicative products as thermorelay is supply of operating curve constancy (force, deformation and operation temperatures at a given rigidity of counterbody). The most and sometimes even the determinant factor is the force, that develops in material with shape memory alloys (SMA) while heating by the given temperature.

The researches were carried out at the alloys of TiNi, which were subject to an annealing at 500 °C, during 30 minutes after cold drawing, with temperatures of martensite transformation (MT):

Ti–50,2 ат% Ni: М_S = 16°С, М_F = 12°С, Т_R' =32°С, А_s = 46°С, А_F = 50°С;

Ti–50,0 ат% Ni: М_S = 62°С, М_F = 40°С, А_s = 80°С, А_F = 86°С.

The effects of generation and relaxation depending on their growth rate and thus decrease of reactive force level at a given values of prestrain un the conditions of infinite rigidity (К ® ¥) and given rigidity of counterbody were studied in complete and incomplete intervals of temperatures MP. In the curve P_r = f (e_пр) two areas can be observed: linear and nonlinear. Relaxational capability of the materials was surveyed from the stress (P_r), registered at the linear area.

Thermomechanical hysteresis closes here, as a rule. However, by the multiple cycle repetition, heat « cooling of the operation temperature change. This fact is connected to the capability of the metals to relaxation, and also to the type of preliminary mechanical or thermal processing of alloy materials with SMA. Certain attention should be paid to the type martensite reaction. It is shown that alloy materials, experiencing the martensite transition В2' ® В19', through the R-phase, provide high convertibility of the deformation in fairly narrow temperature range (till 10°С). Subjects, connected with operability of the active elements while bending and extension under the stress.

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1. Shutoff valve with a shape memory active element