Development of Fe-based shape memory alloys associated with face-centered cubic-hexagonal close-packed martensitic transformations: Part III. microstructures

Yang, Jianguo; Wayman, C.M.

doi:10.1007/bf02647328

Cited by 76 publications

(35 citation statements)

References 19 publications

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“…The main conclusions of this study are : -When the TN temperature is above Ms (alloy B) or slightly below (alloy A) it strongly inhibits the thennal martensitic transformation by stabilization of the y phase, this have also been confirmed by electron microscopy observations [8] -The preexisting thermal martensite does not decrease the SME : for alloys A and B the SME is increased when the alloy is strained at low temperature below Ms, however little thermal martensite is present in this case. For alloy C no difference is observed for SME after deformation at 77K where about 40% thermal martensite is present or at room temperature with little thermal martensite.…”

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confidence: 68%

“…It is not easy to separate the respective importance of these two aspects. Some recent results have clarified this problem.Yang et a1 [6,7,8] have precised the influence of the TN position in relation to the Ms temperature throug three alloys Fe-Mn-Si (Cr-Ni-Co-Al) : A with Ms = 300K, As = 360K and TN = 230K (TN just below Ms) B with Ms < 150K, As < 270K and TN = 260K (TN above M,) C with Ms = 340K, As = 375K and TN = 90K (TN well below Ms) All the samples are solution treated at 1300K for 1 hour and water quenched. They are submitted to bending strains at room temperature (300K) and at liquid nitrogen temperature (77K).…”

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confidence: 99%

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State of the Art in Some Important Fields of Shape Memory Alloys

Guénin

1995

J. Phys. IV France

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Some new results of literature concerning two important fields of shape memory alloys are analyzed and commented : The origin of the shape memory in Fe-based alloys and the origin of the Two way memory effect in f3 phase alloys. Fsbased alloysFebased alloys are able to exhibit Shape Memory Effect (SME) through different kinds of martensitic transformations [I] : f.c.c. to b.c.c. or b.c.t. like in ordered FqPt or ausaged Fe-Ni-Co-Ti; f.c.c. to f.c.t. like in Fe-Pd; f.c.c. to h.c.p. like in Fe-Mn-Si. The two former kinds involve prohibitive cost alloys (Fe-Pt, Fe-Pd) or poor shape memory properies obtained with very particular treatments (Fe-NiCo-Ti). The later kind has received more attention these last years due to relatively good shape memory properties associated to a low alloy cost in addition with the possibility of resistance to corrosion with alloying elements. This development will be focussed on the new results concerning these alloys. The FeMn-Si shape memory alloy has been discovered by Sato et al in single crystals [2, 31. A little later it was observed in polycrystals [4, 51. The nearly perfect SME observed in these alloys appears to be very different from the one of "classical" SM alloys : it involves a distinct crystallography and the transformation is non thermoelastic in nature. The transformation as well as the SM properties are very sensitive to the para-antiferromagnelic transition of the austenite which ocurs at TN (Nee1 temperature). Moreover, in contrast with "classical" SM alloys, the martensitic transformation is also very sensitive to the microstructure (thermomechanical history) of the alloy. It is not easy to separate the respective importance of these two aspects. Some recent results have clarified this problem.Yang et a1 [6,7,8] have precised the influence of the TN position in relation to the Ms temperature throug three alloys Fe-Mn-Si (Cr-Ni-Co-Al) : A with Ms = 300K, As = 360K and TN = 230K (TN just below Ms) B with Ms < 150K, As < 270K and TN = 260K (TN above M,) C with Ms = 340K, As = 375K and TN = 90K (TN well below Ms) All the samples are solution treated at 1300K for 1 hour and water quenched. They are submitted to bending strains at room temperature (300K) and at liquid nitrogen temperature (77K). It is shown that the strain can be divided into three parts :-a "superelastic strain" (SE) including pure elastic strain and which occurs when the stress is suppressed -a "shape memory effect" (SME) which is recovered by hating at about 750K -a "retained strain" (RS) which is the remaining strain An original triangle representation is used to show these values as a function of strain amplitude. The figure 1 shows the behaviour for the three kinds of alloys :The A alloy (high Ms and TN just below) and B alloy (high TN low Ms) exhibit a very large dependance on the temperature at which the strain is performed, whereas the C alloy (high Ms low TN) shows little difference between the two temperatures.Article published online by EDP Sciences and available at http://dx

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confidence: 68%

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confidence: 99%

State of the Art in Some Important Fields of Shape Memory Alloys

Guénin

1995

J. Phys. IV France

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“…A detailed discussion of this has been given by Yang and Wayman. [10] It is observed that in samples that were heat treated in the temperature range of 1000 °C to 1100 °C, the martensite occurred mostly in the thin plate morphology, though the microstructures also occasionally contained wide plates of the martensite. Interestingly, though all habit plane variants of the martensite were observed in the microstructures, there was hardly an instance of variants crossing each other.…”

Section: Resultsmentioning

confidence: 97%

“…The diffraction analysis of the SADPs obtained from the ϩ aЈ region given in Figure 8 by other researchers. [10,19] The stress-induced martensite occurs essentially at the intersections of martensite plates. [10] On the other hand, in the present case, the aЈ martensite occurs as large individual plates that span the entire width of the parent martensite plates.…”

Section: Resultsmentioning

confidence: 99%

The microstructure of an Fe-Mn-Si-Cr-Ni stainless steel shape memory alloy

Maji

Krishnan

Rao

2003

Metall Mater Trans A

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The microstructure and phase stability of the Fe-15Mn-7Si-9Cr-5Ni stainless steel shape memory alloy in the temperature range of 600 °C to 1200 °C was investigated using optical and transmission electron microscopy, X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and chemical analysis techniques. The microstructural studies show that an austenite single-phase field exists in the temperature range of 1000 °C to 1100 °C, above 1100 °C, there exists a three-phase field consisting of austenite, d-ferrite, and the (Fe,Mn) 3 Si intermetallic phase; within the temperature range of 700 °C to 1000 °C, a two-phase field consisting of austenite and the Fe 5 Ni 3 Si 2 type intermetallic phase exists; and below 700 °C, there exists a single austenite phase field. Apart from these equilibrium phases, the austenite grains show the presence of athermal martensite. The athermal aЈ martensite has also been observed for the first time in these stainless steel shape memory alloys and is produced through the ␥--␣Ј transformation sequence.

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“…These steels have the capacity to recover its original shape by the reverse transformation of stress induced ε martensite [1][2][3][4] . Some factors that influence in the capacity of shape memory recovery have been studied, such as the amount of pre-strain, thermomechanical training, alloying elements, deformation temperature and annealing temperature [5][6][7][8][9][10][11][12] .…”

Section: Introductionmentioning

confidence: 99%

Microstructural evaluation on shape recovery in stainless Fe-Mn-Si-Cr-Ni-Co SMA processed by wire drawing

2014

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The effect of the microstructure on the shape recovery in stainless Fe-8Mn-5Si-13Cr-6Ni-12Co shape memory steel (SSMS) was evaluated using tensile tests and reversion temperature of 600°C for a pre-strain of 4%. The tests were performed for a solution treated and annealed conditions at different temperatures after wire drawing of 57% area reduction. The best total shape recovery (TSR) was 83% for a sample deformed and annealed at 850°C. It was concluded that the elastic (or, superelastic) shape recovery (ESR) is high when the austenitic matrix strength is high surpassing the value of shape recovery due to memory effect (SR) and once the austenitic matrix becomes softer, the contribution of SR increases and that of ESR decreases.

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Development of Fe-based shape memory alloys associated with face-centered cubic-hexagonal close-packed martensitic transformations: Part III. microstructures

Cited by 76 publications

References 19 publications

State of the Art in Some Important Fields of Shape Memory Alloys

State of the Art in Some Important Fields of Shape Memory Alloys

The microstructure of an Fe-Mn-Si-Cr-Ni stainless steel shape memory alloy

Microstructural evaluation on shape recovery in stainless Fe-Mn-Si-Cr-Ni-Co SMA processed by wire drawing

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