Atomic force microscope study of stress-induced martensite formation and its reverse transformation in a thermomechanically treated Fe–Mn–Si–Cr–Ni alloy

Bergeon, N.; Kajiwara, Setsuo; Kikuchi, Takehiko

doi:10.1016/s1359-6454(00)00187-7

Cited by 105 publications

(53 citation statements)

References 14 publications

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“…15,16) When Otsuka et al 3) first reported that the SME in Fe-Mn-Si based alloys was greatly improved by "training", they attributed it to the increased yield stress of austenite and the concurrent decrease of the critical stress to induce martensitic transformation. However, Kajiwara and his coworkers 7,17) noticed that this is not the only factor for the improvement in SME.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, it was found very recently by atomic force microscopy study that several cycles of the training are necessary to create a high fraction of the single variant martensite in the Fe-Mn-Si based alloys. 16) Obviously, such a "training" treatment would not be easy for most conceivable applications and, then, would certainly raise the cost of processing and the difficulty of dimensional control in fabrication of the applicable materials and products. Therefore, it is desired to develop new Fe-MnSi based shape memory alloys that need only few cycles of training or even do not need any training.…”

Section: Discussionmentioning

confidence: 99%

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Effect of Nitrogen Addition on Shape Memory Characteristics of Fe-Mn-Si-Cr Alloy

et al. 2002

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Nitrogen-microalloying and partial substitution of Cr for Mn have been employed to enhance the shape memory effect and corrosion resistance of Fe-Mn-Si based alloys. Typically, the tested alloys with nominal composition Fe-25Mn-6Si-5Cr-(0.12-0.14)N in mass% exhibit perfect shape recovery for a 3% pre-strain after only one cycle of thermomechanical training. The related mechanism has been discussed, taking account of the effect of nitrogen on the stacking fault energy (SFE) or the stacking fault probability (P sf ) of the alloy and the strengthening of the austenite matrix. Thermodynamic calculation and P sf measurement showed that the SFE increases with increasing N-content in the concentration range investigated, e.g. less than 0.3 mass%. Thus, the critical stress for the formation of stress-induced martensite increases with N-content. It is believed that the interstitial strengthening of the matrix by nitrogen predominantly contributes to the improvement of shape memory effect. Besides, nitrogen-microalloying remarkably improves the corrosion resistance of the alloys in aqueous solutions containing NaOH and NaCl, but not in HCl solution as indicated by the long-term immersion tests.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effect of Nitrogen Addition on Shape Memory Characteristics of Fe-Mn-Si-Cr Alloy

et al. 2002

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“…This non-thermoelastic or semi-thermoelastic conversion occurred by the creation of stacking faults (SFs) due to the movement of the Shockley partial dislocations (a γ /6 <112>) in the parent phase. SFs are suitable sites for nucleation of the martensite phase; eventually, the ε-phase can be formed by their overlap [12,[17][18][19][20][21][22][23].Although induction melting under an argon gas atmosphere is widely utilized to produce Fe-based SMAs, solid-state routes such as mechanical alloying (MA) can be used to produce the alloys in the powder form [24]. During MA, by applying the high energy collision between ball and particles and consequently the repeated cold welding and fracture of the powders, not only is the alloying process attained but also the synthesis of the non-equilibrium structures such as supersaturated solid solutions, nanocrystalline and amorphous structures, and intermetallic compounds is possible [24][25][26][27][28].…”

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confidence: 99%

Phase transformation during mechano-synthesis of nanocrystalline/amorphous Fe–32Mn–6Si alloys

Amini

Shamsipoor

Ghaffari

et al. 2013

Materials Characterization

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Mechano-synthesis of Fe-32Mn-6Si alloy by mechanical alloying of the elemental powder mixtures was evaluated by running the ball milling process under an inert argon gas atmosphere. In order to characterize the as-milled powders, powder sampling was performed at predetermined intervals from 0.5 to 192 h. X-ray florescence analyzer, X-ray diffraction, scanning electron microscope, and high resolution transmission electron microscope were utilized to investigate the chemical composition, structural evolution, morphological changes, and microstructure of the as-milled powders, respectively.According to the results, the nanocrystalline Fe-Mn-Si alloys were completely synthesized after 48 h of milling. Moreover, the formation of a considerable amount of amorphous phase during the milling process was indicated by quantitative X-ray diffraction analysis as well as high resolution transmission electron microscopy image and its selected area diffraction pattern. It was found that the α-to-γ and subsequently the amorphous-to-crystalline (especially martensite) phase transformation occurred by milling development. © 2013 Elsevier Inc. All rights reserved. Keywords:Fe-Mn-Si shape memory alloys Mechanical alloyingPhase transformation Nanostructural/amorphous phase Microstructure IntroductionFe-Mn-Si alloys are a class of smart materials due to their suitable shape memory effect (SME), excellent machinability and formability, low cost, good weldability and corrosion resistance, and high strength having several industrial applications such as dampers, pipe couplings, big shape memory devices, hard metals or alloys joining, oxygen blowing nozzles and so on [1][2][3][4][5][6][7][8][9][10][11]. The production of stress induced martensite (ε, hcp) from parent austenite phase (γ, fcc) and the reverse transformation (γ to ε) during the heating cycle are the origins of SME in this alloying system [12][13][14][15][16][17][18]. This non-thermoelastic or semi-thermoelastic conversion occurred by the creation of stacking faults (SFs) due to the movement of the Shockley partial dislocations (a γ /6 <112>) in the parent phase. SFs are suitable sites for nucleation of the martensite phase; eventually, the ε-phase can be formed by their overlap [12,[17][18][19][20][21][22][23].Although induction melting under an argon gas atmosphere is widely utilized to produce Fe-based SMAs, solid-state routes such as mechanical alloying (MA) can be used to produce the alloys in the powder form [24]. During MA, by applying the high energy collision between ball and particles and consequently the repeated cold welding and fracture of the powders, not only is the alloying process attained but also the synthesis of the non-equilibrium structures such as supersaturated solid solutions, nanocrystalline and amorphous structures, and intermetallic compounds is possible [24][25][26][27][28].Recently, MA has been widely used to synthesize nanocrystalline and amorphous SMAs [29][30][31], although limited investigations have been done on Fe-Mn-Si alloys.

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“…Besides, assuming that the Shockley partial dislocations, once nucleated, should travel all the way to the grain boundary, the travel path would be smaller, the smaller the grain size is. As shown by Bergeon et al,14) if the deformation is large or the grain size is large, as in this work, more than one variant needs to be activated to accommodate the shear strain. The consequence is the necessity of higher stress to induce the martensite and, for the same amount of macroscopic deformation, the volume fraction of stress-induced martensite would be lower in the samples with larger grain size, as observed in this work.…”

Section: Discussionmentioning

confidence: 88%

Influence of Austenite Grain Size on Mechanical Properties of Stainless SMA

Otubo¹,

Nascimento

Mei

et al. 2002

Mater. Trans.

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This paper presents experimental results relating the initial austenite grain size to bulk hardness, compressive yield stress (σ 0.2% ) and volume fraction of stress-induced ε martensite. It is shown that the bulk hardness obeys quite closely the Hall-Petch equation while the yield stress, σ 0.2% , decreases with decrease of grain size, indicating that the induction of ε martensite mechanically is easier for the materials with finer grains. This fact is corroborated by the observed increase of the volume fraction of stress-induced ε martensite with decrease of grain size. Inversely, after shape recovery heating, the volume fraction of residual stress-induced ε martensite increases as the grain size increases, e.g. the increase in grain size hinders the reversible martensitic transformation.

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Atomic force microscope study of stress-induced martensite formation and its reverse transformation in a thermomechanically treated Fe–Mn–Si–Cr–Ni alloy

Cited by 105 publications

References 14 publications

Effect of Nitrogen Addition on Shape Memory Characteristics of Fe-Mn-Si-Cr Alloy

Effect of Nitrogen Addition on Shape Memory Characteristics of Fe-Mn-Si-Cr Alloy

Phase transformation during mechano-synthesis of nanocrystalline/amorphous Fe–32Mn–6Si alloys

Influence of Austenite Grain Size on Mechanical Properties of Stainless SMA

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