Ferroelastic domains and phases in ferromagnetic nanostructured FePd alloy

Vlasova, N. I.; Щеголева, Н. Н.; Попов, А. Г.; Kandaurova, G. S.

doi:10.1134/s0031918x10110050

Cited by 10 publications

(18 citation statements)

References 10 publications

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“…However, systematic optical polarization and transmission electron microscopy (TEM) studies of the single crystals FePd subjected to annealings both in the absence and in the presence of external uniaxial load have revealed a number of distinctive features of the behavior of meso-and microstructures upon the phase transformation A1 ! L1 0 [22][23][24]. In accordance with current concepts on martensitic [25][26][27] and, in particular, ferroelastic [16,19,[28][29][30] phase transitions, these distinctive features can be considered as the main signs of the formation of a ferroelastic tetragonal disordered phase upon the displacive (martensitic) phase transformation Fm3m !…”

Section: Introductionmentioning

confidence: 66%

“…If annealing is performed in the absence of any external effects, the ordered phase contains crystalline C-domains of all three orientations (C1, C2 and C3). Annealing under a uniaxial tensile or compressive load r||[0 0 1] A1 ensures the predominant growth of C-domains of two (C1, C2) or one (C3) orientations, respectively [7,8,10,22].…”

Section: Methodsmentioning

confidence: 99%

“…On the other hand, optical polarization studies have shown (see previously published data [22][23][24]) that even during the earliest stages of the ordering annealing (15-30 min at T = 500°C) the FePd crystal contains macroscopic ferroelastic domains (FEDs) which have differently oriented optical axes. A pattern of optical polarization contrast observed on the surface (0 0 1) in the FePd crystal after annealing at T = 500°C for 30 min is shown in Fig.…”

Section: Existence Of Macroscopic Ferroelastic Domains At Earliest Stmentioning

confidence: 99%

“…From the changes of the optical polarization contrast upon rotation of the FePd sample around the optical axis of the microscope it follows that the crystal lattice becomes tetragonal: optical axes in the adjacent FEDs are aligned with the axes h1 0 0i and are misoriented with respect to each other by an angle close to p/2, as in a tetragonally ordered crystal [39]. According to the electron microscopy data, the ordered phase is contained in the crystal in the form of optically unresolved nanoscaled regions [8,23,24]. Judging by the intensity relationship I sl /I f = 0.01 of the X-ray superlattice (sl) and fundamental (f) reflections after annealing of the equiatomic FePd alloy at T = 500°C for t = 30 min [7], the volume fraction of the ordered phase is too low to be discerned by the optical polarization method [40].…”

Section: Existence Of Macroscopic Ferroelastic Domains At Earliest Stmentioning

confidence: 99%

“…It is known that in the single crystals and coarse polycrystals FePd the process of long atomic ordering proceeds rather slowly, even at optimal temperatures (500-550°C) [7,8,[22][23][24]. The martensite phases proper rapidly form even at low temperatures and external stresses (elastic and plastic deformation) can favor the martensite transformation [31].…”

Section: Introductionmentioning

confidence: 99%

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Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

et al. 2013

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Specific features of the phase transformation A1 ! L1 0 (space groups Fm3m and P4/mmm, respectively) in single crystals of the equiatomic alloy FePd subjected to annealings both in the absence and in the presence of external uniaxial load, as well as in polycrystalline samples that had undergone severe plastic deformation via high-pressure torsion and subsequent annealing, have been studied. An investigation of the single crystals in a nanostructured state formed at different stages of ordering annealing was performed using optical polarization, thermomagnetic and transmission electron microscopy (TEM) methods. The nanostructured state of the polycrystalline samples FePd after deformation of both disordered and ordered FePd alloys and subsequent annealing was examined with the help of TEM and X-ray techniques. The results obtained were analyzed based on the known concepts of the symmetry theory of phase transitions. It was concluded that the atomic ordering in the FePd alloys is preceded by the formation of a ferroelastic disordered bodycentered tetragonal phase with the structural type A6 and the space group I4/mmm. Experimental data that evidence the existence of a tetragonal disordered phase both in the single crystals and in the polycrystalline samples of FePd after severe plastic deformation and subsequent annealing are reported. Thus, the A1 M A6 M L1 0 phase transformation represents a combination of different types of phase transitions such as cooperative displacement A1 M A6 and ordering A6 M L1 0 of atoms.

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Section: Introductionmentioning

confidence: 66%

Section: Methodsmentioning

confidence: 99%

Section: Existence Of Macroscopic Ferroelastic Domains At Earliest Stmentioning

confidence: 99%

Section: Existence Of Macroscopic Ferroelastic Domains At Earliest Stmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

et al. 2013

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3D coupled thermo-mechanical phase-field modeling of shape memory alloy dynamics via isogeometric analysis

Dhote

Gómez

Melnik

et al. 2015

Computers & Structures

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The paper focuses on numerical simulation of the phase-field (PF) equations for modeling martensitic transformations in shape memory alloys (SMAs), their complex microstructures and thermo-mechanical behavior. The PF model is based on the Landau-Ginzburg potential for the 3D cubic-to-tetragonal phase transformations in SMAs. The treatment of domain walls as diffuse interfaces, leads to a fourth-order differential equation in a strain-based order parameter PF model. The fourth-order equations introduce a number of unexplored numerical challenges because traditional numerical schemes have been primarily applied to second-order problems. We propose isogeometric analysis (IGA) as a numerical formulation for a straightforward solution to the fourth-order differential PF equations using continuously differentiable non-uniform rational B-splines (NURBS). We present microstructure evolution in different geometries of SMA nanostructures under temperature-induced phase transformations to illustrate the geometrical flexibility, accuracy and robustness of our approach. The simulations successfully capture the dynamic thermo-mechanical behavior of SMAs observed experimentally.

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Mössbauer study of fine structure features of equiatomic FePd alloy after severe plastic deformation and ordering annealing

Vlasova

Kleinerman

Serikov

et al. 2014

Journal of Alloys and Compounds

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Ferroelastic domains and phases in ferromagnetic nanostructured FePd alloy

Cited by 10 publications

References 10 publications

Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

3D coupled thermo-mechanical phase-field modeling of shape memory alloy dynamics via isogeometric analysis

Mössbauer study of fine structure features of equiatomic FePd alloy after severe plastic deformation and ordering annealing

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