Crystallization kinetics of Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass in pulsing current pretreatment states

Qiu, Sheng-Bao; Yao, Kefu

doi:10.1016/j.jallcom.2008.07.056

Cited by 17 publications

(7 citation statements)

References 20 publications

(29 reference statements)

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“…Some of the Zr 2 Cu and ZrBe 2 phases (Fig. 1h and i) were also found to nucleate directly from the amorphous matrix and grow into the surroundings, similar to those found in most nanocrystallisation studies91920. However, in our study, the evidence indicates that the dendrite-amorphous matrix interface is the dominant nucleation site for the new crystalline phases.…”

Section: Resultssupporting

confidence: 88%

“…Applying pulsed electric currents with high current density into bulk metallic glasses can accelerate the diffusion and rearrangement of solute atoms over a short period of time910, and therefore promote nanocrystallisation. Johnson et al 11 and Liu et al 12 found that very rapid heating (up to 10 6 K/s) induced by electric current pulse can be used to heat BMGs into the supercooled liquid state without causing crystallisation; in this state, near net-shape thermoplastic processing can be applied.…”

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confidence: 99%

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Multi-scale Characterisation of the 3D Microstructure of a Thermally-Shocked Bulk Metallic Glass Matrix Composite

Zhang

Bodey

Sui

et al. 2016

Sci Rep

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Bulk metallic glass matrix composites (BMGMCs) are a new class of metal alloys which have significantly increased ductility and impact toughness, resulting from the ductile crystalline phases distributed uniformly within the amorphous matrix. However, the 3D structures and their morphologies of such composite at nano and micrometre scale have never been reported before. We have used high density electric currents to thermally shock a Zr-Ti based BMGMC to different temperatures, and used X-ray microtomography, FIB-SEM nanotomography and neutron diffraction to reveal the morphologies, compositions, volume fractions and thermal stabilities of the nano and microstructures. Understanding of these is essential for optimizing the design of BMGMCs and developing viable manufacturing methods.

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Section: Resultssupporting

confidence: 88%

mentioning

confidence: 99%

Multi-scale Characterisation of the 3D Microstructure of a Thermally-Shocked Bulk Metallic Glass Matrix Composite

Zhang

Bodey

Sui

et al. 2016

Sci Rep

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show abstract

“…The previous literature reported that the diffusion and rearrangement of atoms can be accelerated by the extra force generated from the action of HDPC treatment [16][17][18][19][20][21]27,28], which promotes the formation of medium/short range orders (MRO/SRO) and annihilation of free volumes [18,19], and eventually the structural relaxation of amorphous alloy [29]. Holland et al [30] have applied the high density direct current plus isothermal annealing treatment to study the crystallization behavior of Zr 42.6 Ti 12.4 Cu 11.25 Ni 10 Be 23.75 (Vit1A) BMG.…”

Section: Effects Of Crystallization Fractions On the Compressive Behamentioning

confidence: 99%

Effects of crystallization fractions on mechanical properties of Zr-based metallic glass matrix composites

Qiu

Yao

Gong

2010

Sci. China Phys. Mech. Astron.

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The Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 (at.%) bulk metallic glass composites with various crystallization fractions were prepared by pretreating the bulk metallic glassy samples with pulsing current, and then by isothermal annealing at near initial crystallization temperature for different periods of time. The precipitations and crystallization fractions were studied by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), and their effects on mechanical properties of the composite were studied by microhardness, uniaxial compression test and scanning electron microscopy (SEM). The experimental results show that the primary precipitate is quasicrystalline phase and other metastable phases including Be 2 Zr, Zr 2 Cu and FCC would precipitate subsequently. In the initial crystallization process, in which the crystallization fraction increases from 0 to 8.2%, both fracture strength and plastic strain increase, with the maximum plastic strain up to 6.4%. When the crystallization fraction is larger than 8.2%, the fracture strength and the plastic strain decrease sharply. Furthermore, the alloy with low crystallization fraction is fractured by shearing, while for high crystallization fraction it is fractured by splitting and cleavage. The results show that the mechanical properties of the glassy alloy could be optimized by controlling the processing parameters. bulk metallic glass, pulsing current, crystallization fraction, plasticity, shear band PACS: 64.70.Pf, 81.40.Lm, 81.30.Mh, 61.50.KsBulk metallic glasses (BMGs) possess extraordinary properties, such as high strength and strong corrosion resistance, which has attracted much attention from scientists in the area of materials and physics [1][2][3]. Usually the strengths of BMGs come up to theoretical values, much higher than those of the crystalline alloys with the same chemical compositions [1-4]. But BMGs exhibit very limited global plasticity since they deform by shearing through the formation of shear bands that tend to form highly localized shear bands, resulting in crack formation and premature fracture [1][2][3][4][5]. Recently, however, investigations have reported that some BMGs exhibit large plastic strains in compression due to the generation of multiple shear bands [6][7][8][9][10][11]. This implies possibility to enhance the plasticity of BMGs through effectively hindering the highly localized shear along the primary shear bands and promoting the activation of shear bands. The reported results show that one way for improving the ductility of BMGs is to introduce second phases to BMGs by in-situ formation [6] or by isothermal annealing [7], which might benefit the generation of shear bands. For instance, Sun et al. [10] reported that 12% compressive plastic strain could be achieved by in-situ forming spherical crystals within the glassy matrix, while Hofmann et al. [11] reported that Zr-Ti-based bulk metallic glass matrix composites (BMGCs) display tensile plasticity of 8.6%-13.1%. However, effects of different second phases and their cryst...

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“…To date, it is the differential scanning calorimetry (DSC) technique that is used to investigate crystallization processes in both continuous and isothermal heating, including the analyses of the crystallization kinetics of glassy alloys, as has been confirmed in Zr- [14][15][16], Ni- [17], Mg- [11,12,18], Ti- [19] and Ni-based [20][21][22] glassy alloys. In this paper, the crystallization kinetics of Mg 61 Cu 28 Gd 11 and (Mg 61-Cu 28 Gd 11 ) 98 Cd 2 BMGs was investigated in the mode of continuous heating and isothermal annealing.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of crystallization process of Mg–Cu–Gd based bulk metallic glasses

Sun

Shen

et al. 2012

Journal of Non-Crystalline Solids

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Crystallization kinetics of Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass in pulsing current pretreatment states

Cited by 17 publications

References 20 publications

Multi-scale Characterisation of the 3D Microstructure of a Thermally-Shocked Bulk Metallic Glass Matrix Composite

Multi-scale Characterisation of the 3D Microstructure of a Thermally-Shocked Bulk Metallic Glass Matrix Composite

Effects of crystallization fractions on mechanical properties of Zr-based metallic glass matrix composites

Kinetics of crystallization process of Mg–Cu–Gd based bulk metallic glasses

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