Open AccessNucleation centers for martensite with habitus {110} in the shape memory alloys
Author(s) -
М. П. Кащенко,
Н. М. Кащенко,
В. Г. Чащина
Publication year - 2022
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/1213/1/012006
Subject(s) - martensite , nucleation , dislocation , condensed matter physics , materials science , shape memory alloy , symmetry (geometry) , wavelength , alloy , phase (matter) , crystallography , thermodynamics , physics , microstructure , metallurgy , geometry , chemistry , mathematics , quantum mechanics , optoelectronics
The dynamic theory of martensitic transformations (MT) considers the formation of habit planes of martensite crystals as a consequence of the propagation of a controlling wave process (CWP). The general ideology makes it possible, by comparing the observed habits with calculations of the elastic fields of defects (as a rule, dislocations), to identify nucleation centers. In a number of cases (In-Tl alloys, Ni 50 Mn 50 alloys, Heusler alloys …) under MT in the shape memory alloys, {110} habits are observed (in the basis of the initial cubic phase), which often have a fine twin structure with twin boundaries of the same type. This highly symmetric structure is described by the CWP containing longitudinal waves (both relatively long-wavelength ℓ and short-wavelength s ) propagating along the 4-order symmetry axes. In this paper, it is shown that such habits are associated with rectilinear segments of dislocation loops with directions Λ along and Burgers vectors along (or ) orthogonal to Λ , both for sliding and for prismatic loops. The tetragonality, the relative volume change during the MT, and the dependence of the start temperature M s on changes in the concentration of alloy components are also briefly discussed.