ABSTRACT

Using the influence of point defects and their complexes on structural transformations in TiBi-based alloys, it is shown that in the low-stability state of a condensed system (in TiNi, these are the so-called pre-transitional states), the interaction of structural defects can have a significant effect on the structural-phase transformations, and nanoscale objects play a very important role in phase stability in the field of martensitic transformations (MTs).

It is found that the concentration dependences of the onset temperature Ms of the direct MT in stressed and unstressed specimens have different values and different functional dependences. This allows us to hypothesize that the observed effect is associated with the presence of low-stability pre-transitional states in the region of the MT in alloys of this class, and the structure and properties of these states depend on the previous thermomechanical treatments of the system.

The results of studies of the physical properties in multicomponent Ti (Ni, Co, Mo)-alloys, the effect of annealing and thermal cycling on the MT intervals allowed us to establish that thermal cycling through the MI region in microalloyed alloys leads to a slight decrease in the temperature of the onset of the MT and a noticeable increase in the area under the temperature curve of electrical resistivity with saturation after the 20th cycle.