Thermal embrittlement of Fe-based amorphous ribbons

Kumar, Golden; Ohnuma, Masato; Furubayashi, T.; Ohkubo, T.; Hono, K.

doi:10.1016/j.jnoncrysol.2007.08.001

Cited by 36 publications

(18 citation statements)

References 18 publications

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“…The P05 presents an intermediate situation with more than 90% of particles smaller than 63 mm but only 45% smaller than 45 mm. Therefore, the pre-annealing of the ribbons enhances their brittleness as previously observed, for instance, in Fe-based amorphous alloys [12]. Also, short milling times do not induce significant changes in the structure of the sample.…”

Section: Powder Productionsupporting

confidence: 62%

Bulk soft magnetic materials from ball-milled Fe77Nb7B15Cu1 amorphous ribbons

et al. 2009

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Section: Powder Productionsupporting

confidence: 62%

Bulk soft magnetic materials from ball-milled Fe77Nb7B15Cu1 amorphous ribbons

et al. 2009

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“…Such structural relaxation-induced embrittlement effects after sub-T g annealing have been observed in many glass-forming alloys, including iron-, zirconium-, copper-, and magnesium-based amorphous alloys. [36][37][38][39][40] For example, the reduction in the bending fracture strain from 1 to 10 À2 due to sub-T g annealing-induced structural relaxation has been reported for Mg-Cu-Y amorphous alloys. [40] It seems that the irradiation with a laser fluence of 12 J Á cm À2 in our investigation resulted in thermal annealing of the amorphous ribbons below T g of the FeÀBÀSi amorphous alloy.…”

Section: Resultsmentioning

confidence: 99%

Periodically Laser Patterned FeBSi Amorphous Ribbons: Phase Evolution and Mechanical Behavior

et al. 2011

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Bulk metallic glasses or amorphous alloys, in contrast to crystalline materials, exhibit superior properties, such as high hardness, elastic modulus/limits, and corrosion/wear resistance because of their disordered atomic structure without long-range periodicity. [1][2][3][4] These alloys are attracting increasing attention as potential materials for a range of applications in structural, biomedical, and microelectronic industries. [5][6][7][8][9][10][11] However, the actual utilization of amorphous materials in practical applications is limited due to their near-complete brittleness accompanied with strain softening and shear localization. This limited plasticity of amorphous materials is often attributed to the initiation and propagation of localized regions of extensive plastic deformation known as shear bands. [12][13][14][15] There has been a great thrust toward improving the overall global plasticity of amorphous materials by designing amorphous matrix composites reinforced with crystalline phases. [16][17][18] The amorphous matrix composites can also be formed in situ by controlled thermal processing such that partial devitrification results in precipitation of small crystallites in the amorphous matrix. These reinforced crystalline phases are expected to promote the initiation of shear bands and also hinder the propagation of shear bands, thus enhancing the global plasticity of the amorphous materials. [19][20][21][22][23] Most of the ductility-enhancement methods applied to amorphous materials are focused on designing bulk amorphous matrix composites with reinforced crystalline phases. [24,25] However, the role of surface treatments on the deformation and failures of amorphous materials is not well studied. Recently, significant research interests are attracted toward enhancing the plasticity of the amorphous materials by means of surface engineering methods. Most of the interests were invigorated after the publication of a paper by Zhang et al. regarding plasticity enhancement (plasticity in compression and bending) of amorphous materials by controlling the residual state of stresses on the surface of amorphous materials. [26] The compressive surface stresses were induced in the Zr-based amorphous materials by a shot-peening method. The compressive stresses in the peened surfaces caused more shear bands with smaller shear on each band, thus facilitating general continuing plasticity instead of a premature failure on few dominant shear bands. It was observed that the enhanced plasticity in compression and bending is due to a combination of a reduced likelihood of surface cracking and more uniform deformation induced by high population of pre-existing shear bands. [26] More recently, a controlled surface crystallization of amorphous materials by a surface mechanical attrition treatment (SMAT) has beenThe properties of amorphous alloys are significantly influenced by structural relaxation and partial/full crystallization induced by thermal annealing of the alloy. In this paper, the phase evolution and mech...

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“…Speci cally, the direction along the roll-contacted and free surfaces of the ribbon samples (outof-plane direction) should be considered as the solidi cation direction, which is different from in-plane geometry in a micron or sub-micron scale. In addition, the nanocrystallized Fe-based alloys comprising of nanocrystalline grains embedded in the remaining amorphous phase can cause residual stresses due to the difference in thermal expansion coefcients between the crystalline and amorphous phases 12) . The other factors excluding mechanical stress mentioned above are dif cult to achieve using MD simulations, but they would also affect the formation of the L1 0 phase experimentally to some extent.…”

Section: Discussionmentioning

confidence: 99%

Stress-Enhanced Transformations from Hypothetical B2 to Stable L10 and Amorphous to fcc Phases in Fe50Ni50 Binary Alloy by Molecular Dynamic Simulations

et al. 2017

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Molecular dynamics (MD) simulations were performed for an Fe 50 Ni 50 (at.%) alloy with NTp ensemble to keep the number of atoms (N), temperature (T = 673 K), and pressure (p ∼ 101.325 kPa) constant under a GrujicicZhou-type MD potential from an Embedded Atom Method scheme with a cut-off distance of 1 nm. An Fe 50 Ni 50 alloy was initially created as a hypothetical chemically-ordered B2 structure with a 12 × 12 × 12 supercell comprising 3456 atoms. Subsequently, it was annealed at 673 K, without the application of stress, and then under a uniaxial tension of ∼290 MPa, and shear stresses of ∼570 and ∼2940 MPa. The results revealed that stress contributed to a change in the transformation scheme to the L1 0 phase from partially to fully of the system with a reduction of time. On the other hand, an as-quenched amorphous phase under a shear stress of ∼680 MPa, transformed to a disordered fcc-derivative phase. Therefore it is clear that stresses in MD simulations play a crucial role in enhancing the atomic motion during a transformation.

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Thermal embrittlement of Fe-based amorphous ribbons

Cited by 36 publications

References 18 publications

Bulk soft magnetic materials from ball-milled Fe77Nb7B15Cu1 amorphous ribbons

Bulk soft magnetic materials from ball-milled Fe77Nb7B15Cu1 amorphous ribbons

Periodically Laser Patterned FeBSi Amorphous Ribbons: Phase Evolution and Mechanical Behavior

Stress-Enhanced Transformations from Hypothetical B2 to Stable L1<sub>0</sub> and Amorphous to fcc Phases in Fe<sub>50</sub>Ni<sub>50</sub> Binary Alloy by Molecular Dynamic Simulations

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