Martensitic phase transition with two-component order parameter in a stressed cubic crystal

Abstract

Martensitic phase transitions in a stressed cubic crystal are studied by means of Landau theory with a twocomponent order parameter. The stress-temperature phase diagram is analyzed theoretically and is shown to consist of six essentially different regions isolated by the liability lines of austenite, tetragonai martensitic and orthorhombic martensitic phases. The triple point is also present in the phase diagram. The role of the cubic term in the Landau-Ginzburg potential in the description of the phase transition properties is emphasized.

Shape memory ferromagnets

“…The T vs. P and T vs. H phase diagrams of some Ni 2+x Mn 1−x Ga alloys have been calculated in Refs [198,206,239,240,[242][243][244][245].…”

“…Landau theory of phase transitions has been used to describe the given transition. This theory was used to study transitions only in the elastic subsystem [193][194][195][196][197][198] and transitions in systems where the structural and magnetic order parameters interact [22,199]. As applied to phase transitions in Ni 2+x Mn 1−x Ga alloys, Landau theory has been developed in Refs [66,67,91,[200][201][202][203][204][205][206][207][208][209][210][211][212][213][214][215].…”

The Symmetry-Conforming Theory of Martensite Aging

“…[4][5][6][7]). For the sake of certainty the Landau theory will be applied below to the description of aging of martensite formed as the result of cubic-tetragonal MT.…”

Strain-induced interface reconstruction in epitaxial heterostructures

“…Specifically, the strain e 1 varies from positive (i.e., expansional) to negative (i.e., compressional) with decreasing the magnitude of a 2 . A small a 2 absolute value is however expected from the principle e 1 << e 2 , e 3 for all martensitic transformations 28,29 . Moreover, a small a 2 leads to negative e 1 and e 3 , in accordance with the empirical principle for the ferroelastic transitions of close-packed solids, i.e., that cooling of the solid is usually accompanied by a decrease of volume.…”

“…Specifically, in TMO heterostructures the dilatational strain e 1 , which is concommitant to e 3 25,26 , exhibits measurable compression indicating its importance in their structural properties 6 . In ferroelasticity theory, the strain energy density F of a material undergoing a CTT structural transition is expanded in powers of the invariants of the strain tensor and their products around the energy of the parent phase [24][25][26][27][28][29] . Thus, the functional F is expressed solely in terms of the e i 's and their spatial derivatives.…”