Nucleation and growth in bulk metallic glass under high pressure investigated using <i>in situ</i> x-ray diffraction

Wang, W. H.; Wen, Ping; Zhao, Dongdong; Pan, M. X.; Okada, Taku; Utsumi, Wataru

doi:10.1063/1.1636517

Cited by 21 publications

(12 citation statements)

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“…Pressure has two kinds of different effects for nucleation and growth of the crystalline. Firstly, pressure will promote the homogenous formation of small nuclei in amorphous matrix due to decreasing nucleation activation energy [32]. Secondly, the structural disorder driven by pressure stress would suppress long-range atomic diffusion; thereby suppressing the growth of the crystalline.…”

Section: Resultsmentioning

confidence: 99%

Influence of temperature on viscous flow deformation of Zr55Cu30Al10Ni5 bulk glassy alloy in supercooled liquid region

et al. 2007

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Section: Resultsmentioning

confidence: 99%

Influence of temperature on viscous flow deformation of Zr55Cu30Al10Ni5 bulk glassy alloy in supercooled liquid region

et al. 2007

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“…plasticity and ductility) are, thus, controlled by the individual and collective behavior of the shear bands. Therefore, the initiation and propagation of localized shear bands in metallic glasses has been the subject of both theoretical and experimental investigation for number of years [8][9][10][11][12][13][14][15][16][17][18]. However, the precise nature of initiation and propagation of shear bands as well as the possible mechanisms for enhancing the plasticity of BMGs still remain uncertain.…”

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confidence: 99%

Behavior of multiple shear bands in Zr-based bulk metallic glass

Liu

Dai

Bai

et al. 2005

Materials Chemistry and Physics

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The deformation behavior of Zr 41.2 Ti 13.8 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass was studied by in situ scanning electron microscopy (SEM) quasi-static uniaxial compression tests at room temperature. Multiple shear bands were observed with a large plasticity. Microscopic examination demonstrates that slipping, branching and intersecting of multiple shear bands are the main mechanisms for enhancing the plasticity of this metallic glass. Additionally, nano/micro-scale voids and cracks at the intersecting sites of shear bands and preferential etching of shear bands were observed as well. These observations demonstrated that the formation of shear bands in bulk metallic glasses is resulted mainly from local free volume coalescence. © 2005 Elsevier B.V. All rights reserved. Recently, bulk metallic glasses (BMGs) have attracted large interest due to their unique physical, mechanical and chemical properties [1][2][3][4][5][6]. However, BMGs loaded under unconstrained conditions usually fail catastrophically with little global plasticity. This deformation behavior has limited the application of BMGs as engineering material so far. At low temperatures (well below the glass transition), plastic deformation of BMGs is usually localized into thin shear bands [7]. Many macroscopic mechanical properties (e.g. plasticity and ductility) are, thus, controlled by the individual and collective behavior of the shear bands. Therefore, the initiation and propagation of localized shear bands in metallic glasses has been the subject of both theoretical and experimental investigation for number of years [8][9][10][11][12][13][14][15][16][17][18]. However, the precise nature of initiation and propagation of shear bands as well as the possible mechanisms for enhancing the plasticity of BMGs still remain uncertain.In the present letter, the plastic deformation behavior of Zr 41 gated by in situ scanning electron microscopy (SEM) quasistatic uniaxial compression experiments at room temperature. The mechanisms for enhancing the plasticity in this alloy are elucidated. The observed nano/micro-scale voids and cracks at the intersecting sites of shear bands as well as the preferential etching of shear bands provide some evidences to support the free volume theory of the formation of shear bands in metallic glasses [12,13]. Zr 41.2 Ti 13.8 Cu 12.5 Ni 10 Be 22.5 bulk metallic glass was produced by arc melting the pure elements together under a purified Ar atmosphere in ingots of the desired composition, each ingot was then re-melted twice to ensure a homogeneous composition. From these ingots 8 mm diameter rods of metallic glass were prepared by suction casting the molten alloy into a copper mold. The cylinders, thus obtained were confirmed to be non-crystalline by conventional X-ray diffraction.The samples were machined into dog bone-like shape to ensure that the deformation occurs in the middle constraint region of the specimen. The dimensions of the deformation region are 2.0 mm × 2.0 mm × 1.0 mm. For microscopic observations, the...

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“…Such stresses could reach up to 1 GPa, 6 which could result in the increase of the crystallization temperature as a result of the suppression of atomic mobility. [15][16][17] Since partial crystallization of initially amorphous microwire results into formation of ferromagnetic fcc-͑Fe,Ni͒ phase, its presence and temperature behavior can be also studied by measuring the temperature dependence of magnetization M S ͑T͒ ͑Fig. 2͒.…”

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Nanocrystalline glass-coated FeNiMoB microwires

Komova

Varga

et al. 2008

Applied Physics Letters

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The evolution of the structure of glass-coated Fe 40 Ni 38 Mo 4 B 16 amorphous microwire with thermal treatments and its interplay with magnetism has been studied. As shown by x-ray diffraction, a primary crystallization process resulted into formation of ␥-͑Fe, Ni͒ nanocrystallites embedded in a residual amorphous matrix. The evolution of the saturation magnetization and the switching field after different thermal treatment was studied. Amorphous glass-coated microwires based on FeNi exhibit magnetic bistability even in the nanocrystalline state. This is explained by the high magnetoelastic anisotropy, which is also responsible for magnetic hardening after annealing at the temperatures above 670 K. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2969057͔Amorphous and nanocrystalline ferromagnetic microwires covered by a glass coating are very attractive material for applications, mainly as sensing elements in various sensors ͑i.e., magnetic field, coding, etc.͒, due to their outstanding magnetic characteristics, small dimensions and reliability on electrical, mechanical, and corrosive external effects ͑as a result of the Pyrex coating͒.1 These microwires, prepared by quenching and drawing technique, consist of a magnetic nucleus ͑with diameter from 1 -30 m͒ coated by a Pyrexlike glass ͑thickness of 2 -20 m͒. Due to their amorphous nature, magnetoelastic and shape anisotropy contributions govern their magnetic properties. As a result of abovementioned anisotropies, the domain structure of microwires with positive magnetostriction consists of single axial domain and their magnetization process is characteristic of the bistable behavior. 1,2The nanocrystalline microwires have been subject of different studies starting from Finemet based microwires, 3-7 as well as the Nanoperm based ones.8 Such nanocrystalline microwires are usually prepared by heat treatment. However, the microwires undergo strong stresses during the annealing due to the different thermal expansion coefficients of the metallic nucleus and the glass coating. As a result, a ␥-Fe phase appears in annealed glass-coated Finemet microwires instead of desired ␣-͑Fe, Si͒ phase.6,7 When the annealing is performed under high pressure, the formation of ␥-Fe phase is energetically more favorable due to its higher pack density, However, the ␥-Fe phase is nonmagnetic and deteriorates the good soft magnetic properties of nanocrystalline microwires. 6,7 It has been recently shown that partial crystallization of Fe 40 Ni 38 Mo 4 B 16 ribbon leads to the formation of nanocrystalline materials with ␥-͑Fe, Ni͒ nanocrystals having diameter of 10 nm.9 Annealing of such samples at T a = 700 K has been shown to be the optimum annealing temperature to obtain nanocrystalline Fe 40 Ni 38 Mo 4 B 16 alloy with optimized soft magnetic properties ͑lowest magnetostriction, lowest coercive field, and highest initial susceptibility͒. 10,11Since ␥-͑Fe, Ni͒ phase is ferromagnetic contrary to the paramagnetic ␥-Fe phase, it is a promising candidate for preparation of soft magne...

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Nucleation and growth in bulk metallic glass under high pressure investigated using in situ x-ray diffraction

Abstract: Articles you may be interested inStructural stability and compressibility of group IV transition metals-based bulk metallic glasses under high pressure

Cited by 21 publications

References 15 publications

Influence of temperature on viscous flow deformation of Zr55Cu30Al10Ni5 bulk glassy alloy in supercooled liquid region

Influence of temperature on viscous flow deformation of Zr55Cu30Al10Ni5 bulk glassy alloy in supercooled liquid region

Behavior of multiple shear bands in Zr-based bulk metallic glass

Nanocrystalline glass-coated FeNiMoB microwires

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