Fracture toughness determination for a beryllium-bearing bulk metallic glass

Conner, R.D.; Rosakis, Ares J.; Johnson, W. L.; Owen, David M.

doi:10.1016/s1359-6462(97)00250-9

Cited by 182 publications

(88 citation statements)

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“…The sample was then cycled in torsion (0.05°/second under rotational control) to surface shear stresses of nominally 1000 MPa. The shear modulus was determined to be 31 GPa, in close agreement with the previously reported value of 34 GPa for the same alloy [2]. No corrections for the finite torsional stiffness of the machine were performed in order to determine the shear modulus of the material, indicating that the machine is exceptionally stiff in torsion and meets the stability condition expressed in Equation 20.…”

Section: Ratcheting Of Ti-6al-4vsupporting

confidence: 85%

“…Cylindrical dogbone specimens with radii of 1.5 mm and gage lengths of 20 mm were electrode discharge machined (using low power and water cooling to prevent crystallization) from cast rods (12.5 mm diameter) provided by Liquid Metal Technologies, Inc. A uniaxial tension stress of 920 MPa was imposed and maintained constant under load control while the sample was cycled in shear. As with the titanium samples, this stress is nominally half of the tensile yield strength (1.9 GPa for Vitreloy 1) [2]. The sample was then cycled in torsion (0.05°/second under rotational control) to surface shear stresses of nominally 1000 MPa.…”

Section: Ratcheting Of Ti-6al-4vmentioning

confidence: 99%

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The Prospects for Mechanical Ratcheting of Bulk Metallic Glasses

2003

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The major mechanical shortcoming of metallic glasses is their limited ductility at room temperature. Monolithic metallic glasses sustain only a few percent plastic strain when subjected to uniaxial compression and essentially no plastic strain under tension. Here we describe a room temperature deformation process that may have the potential to overcome the limited ductility of monolithic metallic glasses and achieve large plastic strains. By subjecting a metallic glass sample to cyclic torsion, the glass is brought to the yield surface; the superposition of a small uniaxial stress (much smaller than the yield stress) should then produce increments in plastic strain along the tensile axis. This accumulation of strain during cyclic loading, commonly known as ratcheting, has been extensively investigated in stainless and carbon steel alloys, but has not been previously studied in metallic glasses. We have successfully demonstrated the application of this ratcheting technique of cyclic torsion with superimposed tension for polycrystalline Ti–6Al–4V. Our stability analyses indicate that the plastic deformation of materials exhibiting elastic–perfectly plastic constitutive behavior such as metallic glasses should be stable under cyclic torsion, however, results obtained thus far are inconclusive.

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Section: Ratcheting Of Ti-6al-4vsupporting

confidence: 85%

Section: Ratcheting Of Ti-6al-4vmentioning

confidence: 99%

The Prospects for Mechanical Ratcheting of Bulk Metallic Glasses

2003

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“…Amorphous materials have a variety of advantages such as large elastic limit, wear resistance and random packing of atoms. This class of materials has many promising properties, e.g., extremely high strength and hardness combined with relatively high fracture toughness, as well as good wear and corrosion resistance [4][5][6][7][8][9][10]. Therefore, porous amorphous materials combined with materials have many advantages [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Co Oxidation Properties Of Selective Dissoluted Metallic Glass Composites

Kim¹,

Lee²,

Kim³

et al. 2015

Archives of Metallurgy and Materials

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UTLENIANIE WYBRANYCH ROZCIEŃCZONYCH KOMPOZYTÓW SZKIEŁ METALICZNYCHPorous metallic materials have been widely used in many fields including aerospace, atomic energy, electro chemistry and environmental protection. Their unique structures make them very useful as lightweight structural materials, fluid filters, porous electrodes and catalyst supports. In this study, we fabricated Ni-based porous metallic glasses having uniformly dispersed micro meter pores by the sequential processes of ball-milling and chemical dissolution method. We investigated the application of our porous metal supported for Pt catalyst. The oxidation test was performed in an atmosphere of 1% CO and 3% O 2 . Microstructure observation was performed by using a scanning electron microscope. Oxidation properties and BET (Brunauer, Emmett, and Teller) were analyzed to understand porous structure developments. The results indicated that CO Oxidation reaction was dependent on the specific surface area.

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“…Indeed, many toughness measurements on BMG materials reported in the literature [11][12][13][14][15] are inaccurate due to problems of inappropriate measurement techniques ͑e.g., the area under a compression stress/strain curve͒, absence of sharp stress concentrators ͑e.g., using a relatively blunt notch rather than a fatigue precrack͒ and insufficient test-sample size. Moreover, while single-value measurements, such as K Ic , properly define the toughness of nominally brittle materials, they can be insufficient for alloys displaying extensive plastic deformation and subcritical cracking, as can occur in many BMG composites.…”

mentioning

confidence: 99%

Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites

Launey

Hofmann

Suh

et al. 2009

Applied Physics Letters

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Nonlinear-elastic fracture mechanics methods are used to assess the fracture toughness of bulk metallic glass ͑BMG͒ composites; results are compared with similar measurements for other monolithic and composite BMG alloys. Mechanistically, plastic shielding gives rise to characteristic resistance-curve behavior where the fracture resistance increases with crack extension. Specifically, confinement of damage by second-phase dendrites is shown to result in enhancement of the toughness by nearly an order of magnitude relative to unreinforced glass. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3156026͔The absence of microstructure in monolithic bulk metallic glasses ͑BMGs͒ can lead to marked strain localization and rapid shear-band propagation. 1,2 This effect, which causes extremely low macroscopic plastic deformability, can be devastating to mechanical performance in that properties that are limited by the extension of cracks, such as tensile ductility, toughness, and fatigue resistance, can become severely compromised. Specifically, unstable fracture can ensue in monolithic BMGs along a single shear band with essentially zero macroscopic ductility, 3,4 such that the toughness is far lower than in comparable crystalline alloys. The essential element to developing high toughness in BMGs is to prevent single shear-band failures. By introducing a second phase in form of crystalline dendrites and by matching microstructural length scales ͑i.e., interdendritic spacing͒ to the mechanical length scales ͑i.e., critical crack size for failure͒, nonlocalized plasticity in metallic glasses can be enhanced significantly. [5][6][7] Indeed, the recent development of in situ bulk metallic glass-matrix composites has shown that provided this phase acts to arrest shear-band propagation over appropriate size scales, 8-10 the problems of poor ductility, toughness, and fatigue resistance can be mitigated.One problem here is that the new composite BMGs are undoubtedly far tougher than monolithic BMGs or some earlier BMG composites and current processing methods often cannot make section sizes large enough to meet the critical validity requirements for accurate fracture mechanics measurements, i.e., not meeting fracture mechanics requirements for valid stress intensity K-or J-dominated crack-tip fields and/or for plane-strain constraint. Indeed, many toughness measurements on BMG materials reported in the literature [11][12][13][14][15] are inaccurate due to problems of inappropriate measurement techniques ͑e.g., the area under a compression stress/strain curve͒, absence of sharp stress concentrators ͑e.g., using a relatively blunt notch rather than a fatigue precrack͒ and insufficient test-sample size. Moreover, while single-value measurements, such as K Ic , properly define the toughness of nominally brittle materials, they can be insufficient for alloys displaying extensive plastic deformation and subcritical cracking, as can occur in many BMG composites. Stable crack growth in metallic glasses is not generally observed and ...

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Fracture toughness determination for a beryllium-bearing bulk metallic glass

Cited by 182 publications

References 2 publications

The Prospects for Mechanical Ratcheting of Bulk Metallic Glasses

The Prospects for Mechanical Ratcheting of Bulk Metallic Glasses

Co Oxidation Properties Of Selective Dissoluted Metallic Glass Composites

Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites

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