Open AccessМеханизм влияния размера нанокристаллов на параметры кривых псевдоупругой и термоупругой деформации сплавов с эффектом памяти формы
Author(s) -
G. A. Malygin
Publication year - 2019
Publication title -
fizika tverdogo tela
Language(s) - English
Resource type - Journals
eISSN - 1726-7498
pISSN - 0367-3294
DOI - 10.21883/ftt.2019.02.47128.255
Subject(s) - materials science , martensite , diffusionless transformation , nanocrystal , condensed matter physics , mesoscopic physics , hardening (computing) , thermodynamics , austenite , shape memory alloy , phase transition , metallurgy , composite material , nanotechnology , microstructure , physics , layer (electronics)
The data available in the literature on the influence of the nanocrystal sizes of alloys with the shape memory effect on the parameters of the curves of their pseudoelastic and thermoelastic deformation are analyzed in the framework of the theory of diffuse martensitic transitions (DMT). The peculiarity of the DMT theory is that it is based on both thermodynamic and kinetic relationships that make it sensitive to the alloy structure on the mesoscopic scale. This enables one to state the functional dependence of the parameter of the martensitic deformation of the nanocrystals on the size of their cross section D . As a result of the analysis, it is found that the coefficient of the strain (martensitic) hardening and the hysteresis of the pseudoelastic strain curves of submicrocrystals of the Ni_54Fe_19Ga_27 are changed with D by law 1/ D ^2. The temperature range ( M _ s – M _ f ) of the martensitic transition in TiNi alloy nanocrystals is changed by analogy law. These dependences are results of the constrained displacement of dislocations of the phase transformation by transverse sizes of the crystal. A kinetic mechanism of the appearance of the critical nanocrystal size D _ k is established; the transition of austenite to martensite does not occur at transverse crystal sizes smaller than the critical size.