Characterization of Fe–Mn–Si–Cr shape memory alloys containing VN precipitates

Kubo, Hiroshi; Nakamura, Keisuke; Farjami, Sahar; Maruyama, Toru

doi:10.1016/j.msea.2003.10.359

Cited by 52 publications

(31 citation statements)

References 6 publications

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“…However, the grain boundaries in (b) are etched deeper than those in (a), because large amounts of VN compounds are formed at grain boundaries in the sample (b), while fairly small precipitates have already started to form at grain boundaries of the annealed specimens. 13) Such fine precipitates anchor the grain boundaries and prevent grain growth of the alloy. It is also clear from the aligned stripes of " martensite inside the grains that the M s temperature is slightly above the room temperature; and by comparing the (a) and (b) pictures, that the volume fraction of " martensite increases with increasing aging time.…”

Section: Microstructuresmentioning

confidence: 99%

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Shape Memory Effect and Crystallographic Investigation in VN Containing Fe-Mn-Si-Cr Alloys

2004

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An industrial application of Fe-based shape memory alloys for joining the pipes in tunnel making constructions requires the proof stress over 400 MPa and 3.5% shape recovery strain. To meet such standards in civil engineering, the Fe-base shape memory alloy containing highdensity of coherent VN precipitates has been developed by designing the composition of the Fe-28Mn-6Si-5Cr (mass%) alloy containing 1.5 vol% VN compounds. In order to make clear the mechanism of enhancement of the proof stress and shape recovery strain, crystallographic investigations were carried out using optical microscopy, X-ray diffraction and high-resolution electron microscopy. The {111}-composed octahedral shaped VN precipitates are formed coherently with a cube-to-cube orientation relationship with the matrix, i.e., ð001Þ P k ð001Þ M and ½100 P k ½100 M . The precipitates are surrounded by the misfit dislocations at every 8 layers of the (100) planes, which is in agreement with the estimation of the lattice mismatch between the precipitate and the matrix phase. The enhancement of shape recovery is explained by the reversible movement of transformation dislocations left around the precipitates in connection to the residual stress yielded by martensite transformation around the precipitates. It is also suggested that the recovery strain could be proportional to the total number of precipitates.

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Section: Microstructuresmentioning

confidence: 99%

“…It is known from the X-ray diffraction analysis that the VN compound has a NaCl type crystal structure with the lattice constant a VN ¼ 0:411 nm, which is 15% larger than the lattice constant of the matrix, a ¼ 0:358 nm. 13) In Fig. 2(c), the high-resolution electron micrograph of the precipitate observed in [100] zone is shown.…”

Section: Microstructuresmentioning

confidence: 99%

Shape Memory Effect and Crystallographic Investigation in VN Containing Fe-Mn-Si-Cr Alloys

2004

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“…Many researchers have attempted to substitute or add elements with reference to the factors to improve the SME. Although a number of success have been reported [10,11,12], the Si content is always approx. 6% (hereinafter compositions are shown in mass%).…”

Section: Introductionmentioning

confidence: 99%

Role of Si on the shape memory property of Fe-Mn-Si-C based alloys

Koyama

Sawaguchi

Murakami

et al. 2009

ESOMAT 2009 - 8th European Symposium on Martensitic Transformations

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Abstract. Si content dependence of the shape memory effect (SME) associated with the -martensitic transformation has been investigated in Fe-17Mn-xSi-0.3C (x=0,2,4,6) alloys (mass%). By conducting tensile deformations and subsequent heating to above the A f , it has been found that reduction of mere 2% Si content from 6% to 4% obviously deteriorates the SME. The Neel and M s temperatures in both Fe-17Mn4%Si-0.3C and Fe-17Mn6%Si-0.3C alloys are content with the conditions concerning the good SME. By obtaining stress-strain curves at various temperatures, it has been found that the Fe17Mn-4Si-0.3C alloy has similar critical stresses for -martensitic transformation and slip deformation to the critical stresses in the Fe-17Mn-6Si-0.3C alloy. As a consequence, the SME in Fe-Mn-Si-C system sometimes does not appear, even ifmartensitic transformation preferentially occurs.

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“…[3][4][5][6][7][8][9][10][11] The origin of the SME in this alloy is the reversion of the stress-induced "-martensite phase to the parent -austenite that occurs by the movements of the Shockley partial dislocations on heating the material above the A f temperature. 1,2,12) Among the proposed methods of improving the SME of Fe-Mn-Si based shape memory alloys, precipitation hardening seems to be a suitable one to the industrial applications without the necessity of performing repeated thermal cycles and deformation.…”

Section: Introductionmentioning

confidence: 99%

“…1,2,12) Among the proposed methods of improving the SME of Fe-Mn-Si based shape memory alloys, precipitation hardening seems to be a suitable one to the industrial applications without the necessity of performing repeated thermal cycles and deformation. [8][9][10] Depending on the temperature and duration of the heat treatment, precipitates might have different morphologies reportedly changing from a plate and cube shaped morphology at the early stage of aging to an octahedron and tetrakaidecahedron on further aging. [13][14][15] In order to maintain the lattice continuity in a coherent or semicoherent microstructue, the lattice mismatch between the precipitate and the matrix phase is accommodated by elastic displacements of atoms from their equilibrium lattice positions.…”

Section: Introductionmentioning

confidence: 99%

Elastic Energy Analysis of Carbide and Nitride-Type Precipitates in an Fe–Mn–Si–Cr Shape Memory Alloy

Farjami

Kubo

2006

Mater. Trans.

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The application of the microscopic theory of elasticity in a discrete lattice model is made on the transitional metal carbide and nitride precipitates formed in the Fe-Mn-Si-Cr shape memory alloy in conjunction with the improvement of shape memory effect (strain) and the improvement of strength. Two distinguishable methods of analysis have been established using the microscopic theory of elasticity in a discrete lattice model: One is the establishment of the description of precipitate and misfit dislocations in Fourier space. The second is the rigorous estimation of interaction energies among precipitate and misfit dislocations. The results could successfully describe the shape of the precipitate observed in the experimental investigation. It was also concluded that the elastic strain energy increases with the lattice parameter of the precipitate. Among the transition carbides and nitrides under investigations, VN, which revealed the minimum value of the elastic energy, is manifested to be the most favored one for the precipitation enhanced Fe-Mn-Si-Cr shape memory alloy. Homogeneously precipitated VN containing materials could show large deformability, higher strength by precipitation hardening and the higher shape recovery strain due to the nucleation sites of the precipitates in its reverse phase transformation.

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Characterization of Fe–Mn–Si–Cr shape memory alloys containing VN precipitates

Cited by 52 publications

References 6 publications

Shape Memory Effect and Crystallographic Investigation in VN Containing Fe-Mn-Si-Cr Alloys

Shape Memory Effect and Crystallographic Investigation in VN Containing Fe-Mn-Si-Cr Alloys

Role of Si on the shape memory property of Fe-Mn-Si-C based alloys

Elastic Energy Analysis of Carbide and Nitride-Type Precipitates in an Fe–Mn–Si–Cr Shape Memory Alloy

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Characterization of Fe–Mn–Si–Cr shape memory alloys containing VN precipitates

Cited by 52 publications

References 6 publications

Shape Memory Effect and Crystallographic Investigation in VN Containing Fe-Mn-Si-Cr Alloys

Shape Memory Effect and Crystallographic Investigation in VN Containing Fe-Mn-Si-Cr Alloys

Role of Si on the shape memory property of Fe-Mn-Si-C based alloys

Elastic Energy Analysis of Carbide and Nitride-Type Precipitates in an Fe&ndash;Mn&ndash;Si&ndash;Cr Shape Memory Alloy

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Elastic Energy Analysis of Carbide and Nitride-Type Precipitates in an Fe–Mn–Si–Cr Shape Memory Alloy