The Effect of Local Arrangement of Excess Mn on Phase Stability in Ni–Mn–Ga Martensite: An Ab Initio Study

Zelený, Michal; Heczko, Martin; Janovec, Jozef; Holec, David; Straka, Ladislav; Heczko, Oleg

doi:10.1007/s40830-019-00247-0

Cited by 6 publications

(4 citation statements)

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“…When applied to simple problems, for example, the mutual stability of austenite and NM martensite, all three methods provide similar results. [ 118 ] However, studying more complex cases, such as lattice modulation, can only be performed with the SQS approach.…”

Section: Beyond a Perfect Lattice: Off‐stoichiometry Alloying And Ord...mentioning

confidence: 99%

“…Perhaps unsurprisingly, in Mn‐rich alloys, the excess Mn in the Ga sublattice caused antiferromagnetic alignment of the magnetic moments. [ 119,120 ] Zelený et al [ 118 ] showed that such ferrimagnetic ordering affects the stability of two‐layer nanotwins, which allow reliable predictions of the limit for Mn content in modulated phases near 0 K. On the other hand, 10M martensite with ferromagnetic alignment of all Mn atoms was found to be more stable than NM martensite in alloys with a higher Mn content. [ 121 ]…”

Section: Beyond a Perfect Lattice: Off‐stoichiometry Alloying And Ord...mentioning

confidence: 99%

“…Such CPA‐based analyses are available for off‐stoichiometric alloys, [ 154 ] as well as alloys with additional Fe, Co, Cu, [ 155 ] Al, [ 168 ] and Zn. [ 124 ] Calculations based on supercells have shown that the excess Mn atoms in the Ga sublattice prefer to be adjacent to each other, [ 118,121 ] but such configurations are hardly accessible at low temperatures due to the slow diffusion of Mn atoms. [ 110 ]…”

Section: Beyond a Perfect Lattice: Off‐stoichiometry Alloying And Ord...mentioning

confidence: 99%

“…[ 229 ] Except for this work, there are no other results for experimentally observed modulated phases. For the hypothetical modulated 4O structure, the elastic constants were calculated by Zelený et al [ 118 ] Because of their direct relation to lattice instability and the martensitic transition temperature (see Section 3), numerous calculations have been devoted to determining the effect of stoichiometry and alloying on the elastic constants of austenite. The results can be found in literature for Ni‐excess and Mn‐excess alloys [ 147,154 ] as well as for Al‐, [ 96,230 ] Fe‐, Co‐, Cu‐, [ 155 ] Mg‐, [ 152 ] Ti‐, [ 231 ] and B‐doped alloys.…”

Section: Interaction With External Forces: Elastic Constants and Mobi...mentioning

confidence: 99%

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Experimental Observations versus First‐Principles Calculations for Ni–Mn–Ga Ferromagnetic Shape Memory Alloys: A Review

Seiner

Zelený

Sedlák

et al. 2022

Physica Rapid Research Ltrs

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This review summarizes recent advances in first‐principles simulations of the structural, mechanical, and magnetomechanical properties of Ni–Mn–Ga‐based ferromagnetic shape memory alloys from the perspective of experimental characterization. It focuses on calculations that can capture the main features of the low‐temperature phases, particularly the appearance of spatial modulations, the occurrence of intermartensitic transitions, and the high mobility of the twin boundaries, which allows for magnetically induced reorientation. Although the calculations can only be used to interpret some of these features and are not yet ready to be used as a tool for designing new alloys with the required properties, the gap between experimental observations and simulations is narrowing. When experiments and theory are discussed together, new challenges arise for both. In addition, new results on first‐principles‐determined elastic constants of the 10M martensite of Ni–Mn–Ga are presented and discussed with respect to the high mobility of the twin boundaries.

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Section: Beyond a Perfect Lattice: Off‐stoichiometry Alloying And Ord...mentioning

confidence: 99%

Section: Beyond a Perfect Lattice: Off‐stoichiometry Alloying And Ord...mentioning

confidence: 99%

Section: Beyond a Perfect Lattice: Off‐stoichiometry Alloying And Ord...mentioning

confidence: 99%

Section: Interaction With External Forces: Elastic Constants and Mobi...mentioning

confidence: 99%

See 2 more Smart Citations

Experimental Observations versus First‐Principles Calculations for Ni–Mn–Ga Ferromagnetic Shape Memory Alloys: A Review

Seiner

Zelený

Sedlák

et al. 2022

Physica Rapid Research Ltrs

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Shear Deformation of Non-modulated Ni2MnGa Martensite: An Ab Initio Study

Heczko,

Šesták,

Seiner

et al. 2024

Shap. Mem. Superelasticity

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The impact of shear deformation in $$(101)[10\overline{1}]$$ ( 101 ) [ 10 1 ¯ ] system of non-modulated (NM) martensite in Ni2MnGa ferromagnetic shape memory alloy is investigated by means of ab initio atomistic simulations. The shear system is associated with twinning of NM lattice and intermatensitic transformation to modulated structures. The stability of the NM lattice increases with increasing content of Mn. The most realistic shear mechanism for twin reorientation can be approximated by the simple shear mechanism, although the lowest barriers were calculated for pure shear mechanism. The energy barrier between twin variants further reduces due to spontaneous appearance of lattice modulation or, in other words, the nanotwins with thickness of two atomic planes. Such nanotwins appear also on the generalized planar fault energy (GPFE) curve calculated using a newly developed advanced procedure and exhibits even lower energy than the defect free NM structure. These nanotwin doublelayers are also basic building blocks of modulated structures and play an important role in intermartensitic transformation.

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