Degenerate Structure of Transformation Twins and Estimation of Dislocation Density in Martensite Crystals

Кащенко, М. П.; Кащенко, Н. М.; Чащина, В. Г.

doi:10.1134/s1063783419120187

Cited by 3 publications

(1 citation statement)

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“…The results are shown in table 1, are valid for sufficiently large grain sizes of polycrystalline samples, when the ranges of the wave vectors of the ℓand s-waves differ in order of magnitude, but the dispersion of the s-waves can still be ignored. However, for the nanocrystalline state, as in the consideration of degenerate twin structures [13,14], it is necessary to take into account the dispersion of s-waves.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

Nucleation centers for martensite with habitus {110} in the shape memory alloys

Кащенко

Чащина

2022

IOP Conf. Ser.: Mater. Sci. Eng.

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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, Ni50Mn50 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 <001> and Burgers vectors along <010> (or <110>) 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.

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Section: Discussion Of Resultsmentioning

confidence: 99%