Thermal and structural characterization of Fe–Nb–B alloys prepared by mechanical alloying

Suñol, J.J.; González, Ángel; Saurina, J.; Escoda, L.; Bruna, Pere

doi:10.1016/j.msea.2003.10.194

Cited by 31 publications

(22 citation statements)

References 23 publications

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“…Before 20 h milling, the lattice parameter for both alloys (a= 2. [20]. The lower Fe contamination observed in the present study could explain this difference.…”

Section: Microstructural Evolution 431 X-ray Diffractioncontrasting

confidence: 50%

“…% Cr 4.5 Thermal stability Figure 13 shows the DSC scans of different as-milled samples taken at a heating rate of 40 K/min for both alloys. For short milling times, relaxation phenomena [20,24] start at ~700 K. However, for samples milled t ≥50 h for Nb10 and t ≥20 h for Nb5, a deviation from the baseline is detected at ~410 K. For Nb5 alloy milled 50 h or more, (after a supersaturated solid solution is formed), an exothermic peak is observed at ~900 to an activation energy of 1.3 ± 0.1 eV for the broad exotherm at ~750 K of both alloys.For the DSC peaks detected for Nb5 alloy at 900 K and Nb10 at 850 K, Q =3.6 eV and phase, as the crystalline volume fraction does not change significantly (see inset figure 15). After heating up to 1000 K, crystallization of the amorphous phase occurs, evidenced by a clear (110) peak of the -Fe phase.…”

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confidence: 99%

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Mechanical alloying of Fe100−−Nb B (x= 5, 10; y= 10, 15): From pure powder mixture to amorphous phase

et al. 2008

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The mechanical alloying process of Fe 75 Intermetallics. Vol. 16. Núm. 9. 2008. Pag. 1073-1082 http://dx.doi.org/10.1016/j.intermet.2008 2 1 Introduction Nanocrystalline materials are defined by a crystal size below 100 nm. As a limit, amorphous materials are solid systems where the structural long range order is lost.These materials have received much attention due to their physical properties (mechanical and magnetic), which are clearly different from those exhibited by conventional microstructures and, in some cases, improve their technological applicability [1,2,3]. One way to obtain nanocrystalline materials is by partial devitrification of a precursor amorphous alloy during controlled thermal annealing. This technique controls the microstructure of materials and thus optimizes the properties of the final product. Another possibility is mechanical alloying, which has become a very versatile technique to directly produce metastable microstructures (amorphous, nanocrystallines, supersaturate solid solution, etc) [1] from elemental powders or alloys.During this milling process the material is submitted to fracture and cold welding phenomena, as well as intensive plastic deformation, which define the powder morphology, microstruture and properties. The continuous storing of defects in the crystalline phase during milling process unstabilizes it, leading to nanocrystalline and/or amorphous structures [1].Nanocrystalline Fe-M-B type alloys (M= Zr, Nb, etc), so-called Nanoperm [4], are attractive due to their soft magnetic properties after optimum thermal treatment and are used in commercial applications such as telecommunications, micro devices and power electronics [5,6]. Although these systems are generally obtained by rapid quenching and subsequent annealing, nanocrystalline alloys of these compositions can be directly obtained by mechanical alloying of elemental powders. As soft magnetic properties depend on the structure of the material [7,8,9], its structural characterization Intermetallics. Vol. 16. Núm. 9. 2008. Pag. 1073-1082 http://dx.doi.org/10.1016/j.intermet.2008 3 is a very important task to understand the system behavior and to predict its possible technological capabilities.In this study, two Fe 100-x-y Nb x B y (x=5, y=10 and x=10, y=15) alloys were produced by mechanical alloying from a mixture of pure elements and their morphological, compositional and microstructural evolution, as well as their thermal stability, were studied as a function of milling time. The amorphization of the ternary FeNbB system by rapid quenching methods has been studied previously [10]. Whereas compositions similar to Nb10 can be obtained in amorphous structure, those similar to Nb5 can not be obtained as amorphous. ExperimentalFe 100-x-y Nb x B y (x=5, y=10 and x=10, y=15) compositions were prepared by ball milling in a planetary mill Fritsch Pulverisette 4 Vario from elemental powders ( 99 % purity), with particle size d <200 m for Fe and Nb and d <1 mm for B. For simplicity, the studied alloys will be ...

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“…Before 20 h milling, the lattice parameter for both alloys (a= 2. [20]. The lower Fe contamination observed in the present study could explain this difference.…”

Section: Microstructural Evolution 431 X-ray Diffractioncontrasting

confidence: 50%

mentioning

confidence: 99%

Mechanical alloying of Fe100−−Nb B (x= 5, 10; y= 10, 15): From pure powder mixture to amorphous phase

et al. 2008

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“…The observed B crystalline phase in this study by TEM was not detected using XRD in previous studies on the same samples [15] because of the low scattering factor of B atoms. In fact, several authors studying Fe-X-B (X=Nb, Zr,…) systems achieve a final microstructure by ball milling consisting on amorphous and/or supersaturated solid solution nanocrystals without mentioning any B rich phase [6,7,9]. On the other hand, inclusions, discarding this oxide in the systems studied in this paper.…”

Section: Resultsmentioning

confidence: 98%

“…Generally, mechanical alloying is developed from a starting mixture of pure powders, which progressively become alloyed to form an amorphous and/or a supersaturated solid solution. The study of microstructural evolution is frequently followed by X-ray diffraction (XRD) [3,4,5,6,7,8,9], characterizing the phase evolution, average values of microstructural parameters (grain size and microstrains) and compositional information derived from evolution of the average lattice parameter.…”

Section: Introductionmentioning

confidence: 99%

Microstructural evolution characterization of Fe–Nb–B ternary systems processed by ball milling

Ipus

Blázquez

Lozano-Pérez

et al. 2009

Philosophical Magazine

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“…En la aleación B el valor obtenido corresponde a 10 ± 1 nm.. El parámetro de red aumenta con el tiempo de MA siendo mayor que el correspondiente a la fase α-Fe, a = 0.28664 nm, indicando la presencia de otros elementos, en concreto tras 40h de MA el valor es a = 0.2875(7) y a = 0.2871(6) para las aleaciones A y B respectivamente. Análisis estructural complementario mediante espectroscopía Mössbauer de transmisión en aleaciones de composiciones similares confirman la formación de fases nanocristalinas sin una significativa formación de fase amorfa (13).…”

Section: Resultados Y Discusiónunclassified

Desarrollo de materiales de base Fe a partir de la síntesis de precursores por aleado mecánico

González¹,

Martínez²,

Artalejo³

et al. 2005

Bol. Soc. Esp. Ceram. Vidr.

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Se han producido mediante síntesis mecánica aleaciones ricas en Fe, con Zr o Nb y con un no metal, B obteniéndose materiales nanoestructurados con una incipiente fase amorfa (entorno 12%). Tanto el Zr y el Nb como el B facilitan la reducción del tamaño de los nanocristales. Se han optimizado las condiciones de proceso, minimizando el tiempo de molturación. Además, el posterior tratamiento térmico, controlado mediante calorimetría diferencial, de las diferentes aleaciones permite obtener la energía de activación de los procesos de cristalización, con valores entre 280 y 410 kJ mol -1 asociados al crecimiento cristalino. El control del tamaño de los nanocristales se enmarca en el estudio de la cinética de las transformaciones fuera del equilibrio en las que la fase incipiente tiene composición diferente a la de la fase inicial.Palabras clave: aleado mecánico, DSC, XRD, aleaciones metal -no metal. Development of Fe based materials obtained by mechanical alloyingFe rich alloys with ZrNi or Nb and with non metallic B were developed by means of mechanical alloying. The material is nanocrystalline with a minoritary amorphous phase (about 12%). The reduction of the crystallite size is favoured by the addition of Zr, Nb or B. The mechanical alloying parameters were optimised to obtain a nanocrystalline state at low milling time. Furthermore, the apparent activation energy of the crystallisation processes was obtained by thermal treatment, controlled by differential scanning calorimetry. Typical values between 280 and 410 kJ mol -1 are associated to crystalline growth. The control of the crystal size is related to the kinetic study of the non-equilibrium transformations where the incipient phase as different composition that the initial phase. Keywords: mechanical alloying, DSC, XRD, metal -non metal alloys INTRODUCCIÓNLa síntesis de aleaciones mediante la técnica del aleado mecánico (MA) permite la obtención tanto de fases de equilibrio como de no equilibrio, incluyendo materiales nanoestructurados, amorfos, o la extensión de los límites de solubilidad (1-3). Durante el aleado mecánico, las partículas de polvo de los precursores son sometidas a sucesivas fracturas y soldaduras en frío originadas por fenómenos de percusión y de abrasión. Las superficies frescas resultantes tras la fractura facilitan la formación de nuevas partículas y la aleación entre los diferentes precursores en forma de capas con la correspondiente interdifusión.Recientemente, aleaciones de base Fe (conteniendo nanocristales de α-Fe de tamaño inferior a los 100nm) con algún elemento no metálico como el B del tipo Fe-Zr-B o Fe-Nb-B han sido obtenidas mediante nanocristalización inducida térmicamente (4) de aleaciones amorfas previamente producidas en forma de cinta mediante técnicas de solidificación rápida (5-7). Estos materiales son objeto de estudio por sus propiedades magnéticas como la permeabilidad efectiva y la densidad de flujo de saturación magnético (8-10). Sus propiedades les hacen materiales alternativos en dispositivos magnéticos como tran...

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Thermal and structural characterization of Fe–Nb–B alloys prepared by mechanical alloying

Cited by 31 publications

References 23 publications

Mechanical alloying of Fe100−−Nb B (x= 5, 10; y= 10, 15): From pure powder mixture to amorphous phase

Mechanical alloying of Fe100−−Nb B (x= 5, 10; y= 10, 15): From pure powder mixture to amorphous phase

Microstructural evolution characterization of Fe–Nb–B ternary systems processed by ball milling

Desarrollo de materiales de base Fe a partir de la síntesis de precursores por aleado mecánico

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