DYNAMIC MODEL OF NANOCRYSTALLINE REALIZATION OF γ – α MARTENSITIC TRANSFORMATION WITH INCREASED VOLUME EFFECT

10.25712/ASTU.1811-1416.2022.01.003

Abstract

For the γ – α martensitic transformation (MT) in iron-based alloys, an analysis is made of the possibility of wave control of the growth of martensite crystals for cases of an increased value of the relative increase in volume. The principal deformations corresponding to the Pitch distortion tensor are used as the basis for comparison with the typical Bane deformation. The main attention is paid to the analysis of rod-shaped martensitic crystals, the growth of which is controlled by three longitudinal waves propagating along orthogonal axes of symmetry of the fourth order. It is shown that agreement with the values of the main deformations is achieved when the law of wave dispersion is taken into account. The possibility of describing such deformations in three-dimensional deformation schemes, including the fine structure of transformation twins and the limiting variant of the formation of a degenerate dislocation structure, is noted. However, the data on the Pitch interfacial orientational relations are in good agreement with the three-wave scheme of the formation of rod-like crystals. Moreover, the group velocity of at least one of the waves belongs to the short-wavelength range, which leads to the size of the control wavefront in the direction of compression deformation ≈ 1.6 nm. Taking into account the rod-like morphotype of martensite nanocrystals seems promising in interpreting the mechanism of formation of the peripheral zone of lenticular crystals.