Crystal structure and transformation behavior of Ni–Mn–Ga martensites

Richard, M.; Feuchtwanger, J.; Schlagel, Deborah L.; Lograsso, T. A.; Allen, Samuel M.; O’Handley, R. C.

doi:10.1016/j.scriptamat.2006.01.033

Cited by 84 publications

(47 citation statements)

References 16 publications

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“…One common key ingredient is the appearance of intermediate or modulated martensites -5-fold and 10-fold modulated pseudo-tetragonal or orthohombic in the case of Ni-Mn-Ga [15][16][17] and (slightly distorted) face centered tetragonal (fct) in the case of Fe-Pt and Fe-Pd -between the high symmetry austenite and the low-temperature martensite, which is body centered tetragonal in the case of the ferrous alloys.…”

Section: -11mentioning

confidence: 99%

Lattice dynamics and structural stability of orderedFe3Ni,Fe3Pdand
Gruner
¹
,
Adeagbo
²
,
Zayak
³

et al. 2010
Phys. Rev. B

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We investigate the binding surface along the Bain path and phonon dispersion relations for the cubic phase of the ferromagnetic binary alloys Fe3X (X = Ni, Pd, Pt) for L12 and D022 ordered phases from first principles by means of density functional theory. The phonon dispersion relations exhibit a softening of the transverse acoustic mode at the M-point in the L12-phase in accordance with experiments for ordered Fe3Pt. This instability can be associated with a rotational movement of the Fe-atoms around the Ni-group element in the neighboring layers and is accompanied by an extensive reconstruction of the Fermi surface. In addition, we find an incomplete softening in [111] direction which is strongest for Fe3Ni. We conclude that besides the valence electron density also the specific Fe-content and the masses of the alloying partners should be considered as parameters for the design of Fe-based functional magentic materials.

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Section: -11mentioning

confidence: 99%

Lattice dynamics and structural stability of orderedFe3Ni,Fe3Pdand
Gruner
¹
,
Adeagbo
²
,
Zayak
³

et al. 2010
Phys. Rev. B

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“…The deviation may also originate from the lattice parameters, which depend on composition. 3,24 The values in Table I were calculated for c / a ͑10M͒ and b / a ͑14M͒ ratios of 0.939 ͑taken from x-ray diffraction results͒ and 0.937, respectively. 5 For comparison, for a ratio of 0.93, 25 the relief angle is 4.2°, which is the average of the angles ͑ P ͒ measured for the P twins, and within a standard deviation of the individual experimental values ͑Table III͒.…”

Section: Discussionmentioning

confidence: 99%

Transformation twinning of Ni–Mn–Ga characterized with temperature-controlled atomic force microscopy

Reinhold

Watson

Knowlton

et al. 2010

Journal of Applied Physics

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The magnetomechanical properties of ferromagnetic shape memory alloy Ni-Mn-Ga single crystals depend strongly on the twin microstructure, which can be modified through thermomagnetomechanical training. Atomic force microscopy ͑AFM͒ and magnetic force microscopy ͑MFM͒ were used to characterize the evolution of twin microstructures during thermomechanical training of a Ni-Mn-Ga single crystal. Experiments were performed in the martensite phase at 25°C and in the austenite phase at 55°C. Two distinct twinning surface reliefs were observed at room temperature. At elevated temperature ͑55°C͒, the surface relief of one twinning mode disappeared while the other relief remained unchanged. When cooled back to 25°C, the twin surface relief recovered. The relief persisting at elevated temperature specifies the positions of twin boundaries that were present when the sample was polished prior to surface characterization. AFM and MFM following thermomechanical treatment provide a nondestructive method to identify the crystallographic orientation of each twin and of each twin boundary plane. Temperature dependent AFM and MFM experiments reveal the twinning history thereby establishing the technique as a unique predictive tool for revealing the path of the martensitic and reverse transformations of magnetic shape memory alloys.

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“…Nonuniformities in concentration are often due to crystal growth and may lead to significant variation in structure, transformation temperature, and thus in mechanical properties. [45][46][47] Different amounts of nanotwins may have been present at the beginning of the deformation experiments. These nanotwins may have caused microplasticity, which would affect the slope of the linear region.…”

Section: Discussionmentioning

confidence: 99%

Deformation twinning in Ni–Mn–Ga micropillars with 10M martensite

Reinhold

Kiener

Knowlton

et al. 2009

Journal of Applied Physics

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The maximum actuation frequency of magnetic shape-memory alloys ͑MSMAs͒ significantly increases with decreasing size of the transducer making MSMAs interesting candidates for small scale actuator applications. To study the mechanical properties of Ni-Mn-Ga single crystals on small length scales, two single-domain micropillars with dimensions of 10ϫ 15ϫ 30 m 3 were fabricated from a Ni-Mn-Ga monocrystal using dual beam focused ion beam machining. The pillars were oriented such that the crystallographic c direction was perpendicular to the loading direction. The pillars were compressed to maximum stresses of 350 and 50 MPa, respectively. Atomic force microscopy and magnetic force microscopy were performed prior to fabrication of the pillars and following the deformation experiments. Both micropillars were deformed by twinning as evidenced by the stress-strain curve. For one pillar, a permanent deformation of 3.6% was observed and ac twins ͑10M martensite͒ were identified after unloading. For the other pillar, only 0.7% remained upon unloading. No twins were found in this pillar after unloading. The recovery of deformation is discussed in the light of pseudoelastic twinning and twin-substrate interaction. The twinning stress was higher than in similar macroscopic material. However, further studies are needed to substantiate a size effect.

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Crystal structure and transformation behavior of Ni–Mn–Ga martensites

Cited by 84 publications

References 16 publications

Lattice dynamics and structural stability of orderedFe3Ni,Fe3Pdand
Gruner
¹
,
Adeagbo
²
,
Zayak
³

et al. 2010
Phys. Rev. B

Lattice dynamics and structural stability of orderedFe3Ni,Fe3Pdand
Gruner
¹
,
Adeagbo
²
,
Zayak
³

et al. 2010
Phys. Rev. B

Transformation twinning of Ni–Mn–Ga characterized with temperature-controlled atomic force microscopy

Deformation twinning in Ni–Mn–Ga micropillars with 10M martensite

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Crystal structure and transformation behavior of Ni–Mn–Ga martensites

Cited by 84 publications

References 16 publications

Lattice dynamics and structural stability of orderedFe3Ni,Fe3PdandGruner1, Adeagbo2, Zayak3 et al. 2010Phys. Rev. B

Lattice dynamics and structural stability of orderedFe3Ni,Fe3PdandGruner1, Adeagbo2, Zayak3 et al. 2010Phys. Rev. B

Transformation twinning of Ni–Mn–Ga characterized with temperature-controlled atomic force microscopy

Deformation twinning in Ni–Mn–Ga micropillars with 10M martensite

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About

Lattice dynamics and structural stability of orderedFe3Ni,Fe3Pdand
Gruner
¹
,
Adeagbo
²
,
Zayak
³

et al. 2010
Phys. Rev. B

Lattice dynamics and structural stability of orderedFe3Ni,Fe3Pdand
Gruner
¹
,
Adeagbo
²
,
Zayak
³

et al. 2010
Phys. Rev. B