Influence of Mechanical Alloying on the Behavior of Fe-Mn-Si-Cr-Ni Shape Memory Alloys Made by Powder Metallurgy

Pricop, Bogdan; Söyler, U.; Özkal, Burak; Lohan, Nicoleta Monica; Paraschiv, Adrian Liviu; Suru, Marius Gabriel; Bujoreanu, Leandru-Gheorghe

doi:10.4028/www.scientific.net/msf.738-739.237

Cited by 15 publications

(11 citation statements)

References 9 publications

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“…The presence of reverse transformation in the hot forged sample can be associated with larger profile dimensions, revealed on optical microscope and atomic force microscope micrographs and especially with the higher degree of surface unevenness, which indicates the storage of higher amounts of internal stresses, enhanced by the shocks produced during forging and attenuated by the smoothness of rolling process .…”

Section: Resultsmentioning

confidence: 96%

Effects of hot working procedure on surface relief characteristic in an Fe–Mn–Si–Cr shape memory alloy

Suru

Dan²,

Lohan

et al. 2014

Materialwissenschaft Werkst

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The paper reports the evolution of surface relief and shape memory behavior in an Fe-28Mn-6Si-5Cr (mass%) shape memory alloy (SMA) as a function of the applied hot working procedure. The objective of this paper is to discuss the relationship between surface relief characteristic, structural changes and the type of hot working processing. Particular aspects concerning the relief of martensite plates were reported after the alloy was subjected to two types of hot working procedures, namely hot rolling and hot forging at 1273 K. The observations were performed by means of optical (OM) and atomic force (AFM) microscopy, on bi-dimensional and three-dimensional micrographs, corroborated with statistical evaluations. Aiming to reveal the presence of solid phase transitions enabled by hot working, differential scanning calorimetry (DSC) measurements were performed between room temperature and 673 K.Keywords: shape memory alloy / surface relief / hot working / atomic force microscopy / differential scanning calorimetry / phase transition Schlüsselwörter: Formgedächtnislegierung / Oberflächengestalt / Warmbearbeitung / Rasterkraftmikroskopie / Differentielle Scanning-Kalorimetrie / Phasenübergang

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Section: Resultsmentioning

confidence: 96%

Effects of hot working procedure on surface relief characteristic in an Fe–Mn–Si–Cr shape memory alloy

Suru

Dan²,

Lohan

et al. 2014

Materialwissenschaft Werkst

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“…The SEM micrographs show a typical aspect of ε-hcp martensite and some dark regions, at the intersection of ε plates, which were associated with α -bcc martensite. Obviously, the structure of 50_MA_1100 specimen, from Figure 10b, reveals a larger amount of α -bcc martensite (Pricop et al, 2013).…”

Section: Particularities Of α -Bcc Martensitementioning

confidence: 98%

“…FIGURE 10 | Influence of MA degree on the microstructure of specimens pre-strained with 4%: (a) 0_MA_1100 and (b) 50_MA_1100, with thermally induced ε-hcp martensite. The insets display the effects of 4% pre-straining on stress-induced formation of α -bcc martensite (modified after Pricop et al, 2013). The cumulated effects of heat treatments and tensile prestraining degrees were investigated on the hot rolled specimens sintered from as-blended powders, designated as 0_MA_700, 0_MA_800, 0_MA_900, 0_MA_1000 and 0_MA_1100.…”

Section: Thermomechanical Processing and Pre-straining Effectsmentioning

confidence: 99%

Powder Metallurgy: An Alternative for FeMnSiCrNi Shape Memory Alloys Processing

et al. 2020

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In the case of quintenary Fe-Mn-Si-Cr-Ni shape memory alloys (SMAs), ingot metallurgy (IM) has technological shortcomings concerning compositional segregation, imperfect melt-incorporation of Si, demanganization during heating and cooling-induced cracking, which can be effectively surmounted by combining powder metallurgy (PM) with mechanical alloying (MA). The paper reviews the results reported in the processing and characterization of PM-MA'ed FeMnSiCrNi SMAs, with special emphasis on the findings obtained by present authors in the last decade. Specimens with nominal chemical compositions Fe-18Mn-3Si-7Cr-4Ni and Fe-14Mn-6Si-9Cr-5Ni (mass %) were produced by IM and PM. In the latter case various volume fractions of as-blended powders were MA'ed under protective atmosphere, before being pressed and sintered. Further compacting, up to 5% porosity degrees, was achieved by hot rolling. Structural analysis, performed by X-ray diffraction and scanning electron microscopy, revealed the formation of unusually large amounts of α-body centred cubic (bcc) thermally induced martensite. This undesirable martensite seemed to be destabilized by tensile pre-straining, and enabled PM specimens to reach higher stresses than IM ones. The formation and accumulation of α-bcc stress induced martensite was enhanced by tensile pre-straining, mechanical cycling and augmentation of MA'ed powder fraction. It has been argued that the optimization of technological processing parameters of heat treatment (HT) and hot rolling (HR) combined with MA'ed powder fraction caused the augmentation of shape memory effect (SME) magnitude. DMA-temperature scans revealed an increasing tendency of internal friction (tan δ) with MA'ed powder fraction, as well as the presence of two tan δ maxima ascribed to antiferromagneticparamagnetic transition and martensite reversion to austenite, respectively. DMA-strain sweeps emphasized the occurrence of a plateau on the storage modulus vs. strain amplitude variation which was associated with stress-induced formation of ε hexagonal close-packed (hcp)-martensite. In spite of large α-bcc amounts, PM-MA'ed Fe-14Mn-6Si-9Cr-5Ni experienced free-recovery SME which was enhanced by thermomechanical training. Coupling rings, meant to connect vibrating pipes that transport turbulent fluids, being able to mitigate vibrations that could accidentally open the connection, were manufactured and tested.

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“…The microstructure of 0_MA, 50_MA and 14Mn specimens was observed, after appropriate metallographic preparation [21], using a SEM-VEGA II LSH TESCAN microscope, coupled with an EDX-QUANTAX QX2 ROENTEC detector. The average diameter of crystalline grains, of each of the nine different specimens, was statistically determined by means of OptikaView software.…”

Section: Microstructural Characterization and Dynamo-mechanical Analysismentioning

confidence: 99%

Powder metallurgy and mechanical alloying effects on the formation of thermally induced martensite in an FeMnSiCrNi SMA

Pricop

Mihalache

Lohan

et al. 2015

MATEC Web of Conferences

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Abstract. By ingot metallurgy (IM, melting, alloying and casting), powder metallurgy (PM, using as-blended elemental powders) and mechanical alloying (MA of 50 % of particle volume), three types of FeMnSiCrNi shape memory alloy (SMA) specimens were fabricated, respectively. After specimen thickness reduction by hot rolling, solution treatments were applied, at 973 and 1273 K, to thermally induce martensite. The resulting specimens were analysed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), in order to reveal the presence of ε (hexagonal close-packed, hcp) and α' (body centred cubic, bcc) thermally induced martensites. The reversion of thermally induced martensites, to γ (face centred cubic, fcc) austenite, during heating, was confirmed by dynamic mechanical analysis (DMA), which emphasized marked increases of storage modulus and obvious internal friction maxima on DMA thermograms. The results proved that the increase of porosity degree, after PM processing, increased internal friction, while MA enhanced crystallinity degree.

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Influence of Mechanical Alloying on the Behavior of Fe-Mn-Si-Cr-Ni Shape Memory Alloys Made by Powder Metallurgy

Cited by 15 publications

References 9 publications

Effects of hot working procedure on surface relief characteristic in an Fe–Mn–Si–Cr shape memory alloy

Effects of hot working procedure on surface relief characteristic in an Fe–Mn–Si–Cr shape memory alloy

Powder Metallurgy: An Alternative for FeMnSiCrNi Shape Memory Alloys Processing

Powder metallurgy and mechanical alloying effects on the formation of thermally induced martensite in an FeMnSiCrNi SMA

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