Artykuły w czasopismach: „Metallic Glass Specimens”

1

Wu, F. F., Z. F. Zhang i S. X. Mao. "Compressive properties of bulk metallic glass with small aspect ratio". Journal of Materials Research 22, nr 2 (luty 2007): 501–7. http://dx.doi.org/10.1557/jmr.2007.0064.

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The quasi-static compressive deformation behavior of a Vitreloy 1 bulk metallic glass (BMG) with an aspect ratio of 0.25 was investigated. It is found that the friction and the confinement at the specimen–loading platen interface will cause the dramatic increase in the compressive load, leading to higher compressive strength. In particular, the BMG specimens show great plastic-deformation ability, and plenty of interacted, deflected, wavy, or branched shear bands were observed on the surfaces after plastic deformation. The formation of the strongly interacted, deflected, wavy, or branched shear bands can be attributed to the triaxial stress state in the glassy specimens with a very small aspect ratio.

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Zhang, H., L. Z. Liu, Z. F. Zhang, K. Q. Qiu, X. F. Pan, H. F. Zhang i Z. G. Wang. "Deformation and fracture behavior of tungsten fiber-reinforced bulk metallic glass composite subjected to transverse loading". Journal of Materials Research 21, nr 6 (1.06.2006): 1375–84. http://dx.doi.org/10.1557/jmr.2006.0169.

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Deformation and fracture behavior of Zr41.25Ti13.75Ni10Cu12.5Be22.5 bulk metallic glass and its composite containing transverse tungsten fibers in compression were investigated. The monolithic metallic glass and the tungsten fiber composite specimens with aspect ratios of 2 and 1 are shown to have essentially the same ultimate strength under compression. The damage processes in the bulk metallic glass composite consisted of fiber cracking, followed by initiation of shear band in the glassy matrix mainly from the impingement of the fiber crack on the fiber/matrix interface. The site of the shear band initiation in the matrix is consistent with the prediction of finite element modeling. Evidence is present that the tungsten fiber can resist the propagation of the shear band in the glassy matrix. However, the compressive strain to failure substantially decreased in the present composite compared with the composites containing longitudinal tungsten fibers. Finally, the two composite specimens fractured in a shear mode and almost all the tungsten fibers contained cracks.

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Nakai, Yoshikazu, Naoki Sei i Bok Key Kim. "Notched Fatigue of Zr-Based Bulk Metallic Glass". Key Engineering Materials 345-346 (sierpień 2007): 259–62. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.259.

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In the present study, fatigue tests of sharp-notched Zr-based bulk metallic glass (BGM), were conducted under fully reversed cyclic bending, and the fatigue crack initiation mechanisms were clarified by using AFM. The fracture surface was also observed to examine the crack propagation mechanism. The fatigue notch factor was 2.0, while the elastic stress concentration factor is 2.7. From the macroscopic observations of fractured specimen, either tension mode or shear mode fracture morphologies were observed. Either in smooth specimens or notched specimens, no prodigious sign of crack initiation were observed, i.e., fatigue cracks were initiated from shear bands those were formed just before the crack initiation.

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Lu, Tong, Song Ling Liu, Yong Hao Sun, Wei-Hua Wang i Ming-Xiang Pan. "A Free-Volume Model for Thermal Expansion of Metallic Glass". Chinese Physics Letters 39, nr 3 (1.03.2022): 036401. http://dx.doi.org/10.1088/0256-307x/39/3/036401.

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Many mechanical, thermal and transport behaviors of polymers and metallic glasses are interpreted by the free-volume model, whereas their applications on thermal expansion behaviors of glasses is rarely seen. Metallic glass has a range of glassy states depending on cooling rate, making their coefficients of thermal expansion vary with the glassy states. Anharmonicity in the interatomic potential is often used to explain different coefficients of thermal expansion in crystalline metals or in different metallic-glass compositions. However, it is unclear how to quantify the change of anharmonicity in the various states of metallic glass of the same composition and to connect it with coefficient of thermal expansion. In the present work, isothermal annealing is applied, and the dimensional changes are measured for La62Al14Cu11.7Ag2.3Ni5Co5 and Zr52.5Cu17.9Ni14.6Al10Ti5 metallic glasses, from which changes in density and the coefficients of thermal expansion of the specimens are both recorded. The coefficients of thermal expansion linearly decrease with densification reflecting the role of free volume in thermal expansion. Free volume is found to have not only volume but also entity with an effective coefficient of thermal expansion similar to that of gases. Therefore, the local regions containing free volume inside the metallic glass are gas-like instead of liquid-like in terms of thermal expansion behaviors.

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He, Tianbing, Nevaf Ciftci, Volker Uhlenwinkel i Sergio Scudino. "Synthesis of Bulk Zr48Cu36Al8Ag8 Metallic Glass by Hot Pressing of Amorphous Powders". Journal of Manufacturing and Materials Processing 5, nr 1 (9.03.2021): 23. http://dx.doi.org/10.3390/jmmp5010023.

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The critical cooling rate necessary for glass formation via melt solidification poses inherent constraints on sample size using conventional casting techniques. This drawback can be overcome by pressure-assisted sintering of metallic glass powders at temperatures above the glass transition, where the material shows viscous-flow behavior. Partial crystallization during sintering usually exacerbates the inherent brittleness of metallic glasses and thus needs to be avoided. In order to achieve high density of the bulk specimens while avoiding (or minimizing) crystallization, the optimal combination between low viscosity and long incubation time for crystallization must be identified. Here, by carefully selecting the time–temperature window for powder consolidation, we synthesized highly dense Zr48Cu36Ag8Al8 bulk metallic glass (BMG) with mechanical properties comparable with its cast counterpart. The larger ZrCu-based BMG specimens fabricated in this work could then be post-processed by flash-annealing, offering the possibility to fabricate monolithic metallic glasses and glass–matrix composites with enhanced room-temperature plastic deformation.

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Saotome, Yasunori, Suguru Okaniwa, Hisamichi Kimura i Akihisa Inoue. "Superplastic Nanoforging of Pt-Based Metallic Glass with Dies of Zr-BMG and Glassy Carbon Fabricated by Focused Ion Beam". Materials Science Forum 539-543 (marzec 2007): 2088–93. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.2088.

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This paper introduces a technique for fabricating nano-structures through super plastic nano-forging of metallic glass using nano-scale dies that are fabricated by a focused-ion beam (FIB). FIB-machining characteristics of glassy carbon and Zr-based metallic glass have been studied and are useful for fabricating nano-scale dies because of the isotropic homogeneity of their amorphous structures. We used the dies to nano-forge Pt48.75Pd9.75Cu19.5P22 metallic glass. The thin foil specimens were heated in a small furnace and compressively loaded in a small vacuum chamber. Dies, a die-forged 1μm-diameter micro-gear, and both 800 and 400nm periodic nano-structures for optical applications were demonstrated. We observed the effects of thermal expansion and contact angle between the working material and the die materials on nano-formability. Metallic glasses are highly useful as materials for nano-imprinting and as die materials for FIB nano-machining.

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Bruck, H. A., A. J. Rosakis i W. L. Johnson. "The dynamic compressive behavior of beryllium bearing bulk metallic glasses". Journal of Materials Research 11, nr 2 (luty 1996): 503–11. http://dx.doi.org/10.1557/jmr.1996.0060.

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In 1993, a new beryllium bearing bulk metallic glass with the nominal composition Zr41.25Ti13.75Cu12.5Ni10Be22.5 was discovered at Caltech. This metallic glass can be cast as cylindrical rods as large as 16 mm in diameter, which permitted specimens to be fabricated with geometries suitable for dynamic testing. For the first time, the dynamic compressive yield behavior of a metallic glass was characterized at strain rates of 102 to 104/s by using the split Hopkinson pressure bar. A high-speed infrared thermal detector was also used to determine if adiabatic heating occurred during dynamic deformation of the metallic glass. From these tests it appears that the yield stress of the metallic glass is insensitive to strain rate and no adiabatic heating occurs before yielding.

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8

Yang, Yu-Hang, Jun Yi, Na Yang, Wen Liang, Hao-Ran Huang, Bo Huang, Yan-Dong Jia, Xi-Lei Bian i Gang Wang. "Tension-Tension Fatigue Behavior of High-Toughness Zr61Ti2Cu25Al12 Bulk Metallic Glass". Materials 14, nr 11 (25.05.2021): 2815. http://dx.doi.org/10.3390/ma14112815.

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Bulk metallic glasses have application potential in engineering structures due to their exceptional strength and fracture toughness. Their fatigue resistance is very important for the application as well. We report the tension-tension fatigue damage behavior of a Zr61Ti2Cu25Al12 bulk metallic glass, which has the highest fracture toughness among BMGs. The Zr61Ti2Cu25Al12 glass exhibits a tension-tension fatigue endurance limit of 195 MPa, which is higher than that of high-toughness steels. The fracture morphology of the specimens depends on the applied stress amplitude. We found flocks of shear bands, which were perpendicular to the loading direction, on the surface of the fatigue test specimens with stress amplitude higher than the fatigue limit of the glass. The fatigue cracking of the glass initiated from a shear band in a shear band flock. Our work demonstrated that the Zr61Ti2Cu25Al12 glass is a competitive structural material and shed light on improving the fatigue resistance of bulk metallic glasses.

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9

Kuroda, Toshio, Kenji Ikeuchi, Masahiro Shimada, Akihisa Inoue i Hisamichi Kimura. "Micro Flash Welding of Super Duplex Stainless Steel with Zr Metallic Glass Insert". Materials Science Forum 580-582 (czerwiec 2008): 53–56. http://dx.doi.org/10.4028/www.scientific.net/msf.580-582.53.

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Micro flash butt welding of super duplex stainless steel with Zr-based metallic glass insert was carried out using the temperature controlling system. Zr55Cu30Ni5Al10 of Zr-based metallic glass with thickness of 0.05mm and Zr metal with thickness of 0.1mm and 0.5 mm were used as the insert materials, in order to improve weldability. The specimens were mounted on the dies using a Gleeble thermal simulator, and then, flash butt welding was made. After welding, Zrbased metallic glass insert became much thinner than Zr metal insert. The super-cooled liquid in the interface protruded outside due to the superplastic deformation. The formation of the protrusion discharged the oxide films on the butting surfaces and contact surface; resulting in metallurgical bonding through the fresh surfaces. The Fe-Zr metallic compound for Zr-based metallic glass insert was hardly observed. The micro flash butt welding with metallic glass insert was successfully accomplished for super duplex stainless steel.

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10

Wang, Jin Xiang, Xiao Li Zhang, Nan Zhou i Zheng Zhao. "Explosive Compaction of Metallic Glass Particles Reinforced Aluminium Matrix Composites". Advanced Materials Research 189-193 (luty 2011): 2472–76. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.2472.

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In this paper the metallic glass particles reinforced aluminium matrix composites without obvious defects were obtained successfully by explosive compaction of mixed powders. The mass fraction of the amorphous phase is 10%, 15% and 20% respectively in the specimens. The scaning electric microscope micrographs of the composites show that the metallic glass particles are uniformly distributed in the matrix. The x-ray diffraction and differential thermal analysis of the composite specimens show that the amorphous phase is maintained in the composites without crystallization during the compaction. Finally the influences of macro-temperature rise and micro-heat transfer on the crystallization were analyzed.

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11

Sypień, A. "Observation of the Complex Local Crystallization Process in Ti-Zr-Cu-Pd Amorphous Ribbons and Bulk Metallic Glass". Archives of Metallurgy and Materials 58, nr 2 (1.06.2013): 347–50. http://dx.doi.org/10.2478/v10172-012-0196-z.

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In recent years, bulk metallic glasses (BMGs) have attracted much attention, especially concerning the reasons for the high glass-forming ability. To understand properties and glass-forming ability of BMGs, it is important to investigate their atomic structure in details. The structure of the metallic glass, derived from diffraction studies, confines mainly to short-range-order atomic correlations, which are statistically averaged over the glassy specimens. In the present study, local structure of a BMG and ribbons was observed using a high-resolution TEM (TECNAI G2 FEG). The TEM images of the BMG before annealed in the temperature below the crystallization clearly reveal a duplex microstructure consisting of nanocrystalline particles about 5-10 nm in size distributed uniformly in the amorphous matrix. Due to the FFT research the crystalline phases may be indexed as the Cu8Zr3, Cu3Pd, CuTi2 and CuTiZr.

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Sayman, Onur, i Ümran Esendemir. "Rainwater effect on bearing strength of glass–epoxy laminated composite pinned joints". Journal of Composite Materials 50, nr 30 (28.07.2016): 4269–78. http://dx.doi.org/10.1177/0021998315621658.

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Composite materials are used in areas that have varying environmental conditions due to their advantages such as generally higher stiffness- and strength-to-weight ratio, and corrosion resistance compared to metallic alloys. This experimental study is carried out to investigate the bearing strengths and failure modes of woven glass–epoxy composite pinned joints subjected to rainwater. The specimens were immersed in rainwater in a closed plastic container indoors for 20 month periods at room temperature. The ratio of edge-distance-to-hole diameter (E/D) and the ratio of the specimen width-to-hole-diameter (W/D) were selected as parameters. Failure modes were determined by observing the failure regions on the specimens. Damage of immersed and unimmersed specimens was examined using scanning electron misroscopy for the same failure load. Experimental results showed that the bearing load values obtained from the specimens immersed in rainwater decreased in comparison to unimmersed specimens.

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13

Nakai, Yoshikazu, Kenichi Nakagawa i Kohei Mikami. "Effect of Inhomogeneity of Zr-Based Bulk Metallic Glass Plate on Fatigue Strength under Torsion". Materials Science Forum 706-709 (styczeń 2012): 1331–36. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.1331.

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Fatigue tests of Zr-based bulk metallic glass plates were conducted under cyclic-torsion, and the results were compared with those obtained under cyclic-bending and axial-loading. The fatigue strength of axial-loading was lower than that under cyclic-bending because the fatigue strength depends on the cooling rate in the casting process of the material, which is different in the thickness direction. The fatigue strength of plane-bending reflects the strength at the specimen surface while that of axial-loading is determined by the weakest strength in the thickness direction. For cyclic torsion of specimens with rectangular cross-section, the fatigue crack initiation site must be determined by the ratio of specimen width to specimen thickness, and fatigue strength depends on the ratio. Therefore, the criteria for fatigue limit under combined stress for metallic glass should be constructed considering the crack initiation site.

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Zhang, Z. F., J. Eckert i L. Schultz. "Tensile and fatigue fracture mechanisms of a Zr-based bulk metallic glass". Journal of Materials Research 18, nr 2 (luty 2003): 456–65. http://dx.doi.org/10.1557/jmr.2003.0058.

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The tensile and fatigue fracture behavior of Zr59Cu20Al10Ni8Ti3 bulk metallic glass was investigated. It was found that under tensile load the metallic glass always displays brittle shear fracture and the shear fracture plane makes an angle of θT (=54°) with respect to the stress axis, which obviously deviates from the maximum shear stress plane (45°). Under cyclic tension-tension loading, fatigue cracks first initiate along the localized shear bands on the specimen surface, then propagate along a plane basically perpendicular to the stress axis. Tensile fracture surface observations reveal that fracture first originates from some cores, then propagates in a radiate mode, leading to the formation of a veinlike structure and final failure. The fatigue fracture processes of the specimens undergo a propagation stage of fatigue cracks followed by catastrophic failure. Based on these results, a tensile fracture criterion for bulk metallic glasses is proposed by taking the effect of normal stress into account. It is suggested that both normal and shear stresses affect the fracture process of metallic glasses and cause the deviation of the fracture angle away from 45°

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15

Wei, Ran, Juan Tao, Shi Lei Liu, Guo Wen Sun, Shuai Guo i Fu Shan Li. "Effect of B2 Phase Transformation on the Mechanical Behavior of CuZr-Based Bulk Metallic Glass Composites". Materials Science Forum 898 (czerwiec 2017): 672–78. http://dx.doi.org/10.4028/www.scientific.net/msf.898.672.

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The mechanical behavior of CuZr-based bulk metallic glass composites with different B2-CuZr phase transformation ability was investigated. The B2 phase transformation is conducive to enhance the mechanical properties of CuZr-based bulk metallic glass composites. The mechanical properties of the austenitic B2 phase specimens were also studied to understand the mechanism of phase transformation effect. It was found that the B2 phase with martensitic transformation exhibits lower yield strength and stronger work-hardening capability than the B2 phase without martensitic transformation. Thus, the phase transformation effect of B2-CuZr phase, accompanying with its lower yield strength and stronger work-hardening capability, is the main reason for the CuZr-based bulk metallic glass composites possess outstanding mechanical properties.

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Nilsson, Douglas Jutsell, Stanislaw M. Gubanski i Yuriy V. Serdyuk. "Electrical Detection of Degradation in Specimens of HVDC Cable Insulation". Energies 13, nr 15 (1.08.2020): 3963. http://dx.doi.org/10.3390/en13153963.

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One of the challenges in laboratory investigation of degradation and ageing of HVDC cable insulation is related to securing, or in other words, imitating the real service environment of the material specimens. So far, the published data refer to experiments conducted in thermo-oxidative conditions, which is not the case during normal cable operation. In service, the cable insulation is protected by a metallic barrier that blocks the transfer of any substances in and out of the construction. By-products from the cross-linking reactions cannot diffuse out and any foreign substances are blocked from entering the insulation. Thus, in order to generate results that are valid, these conditions must be replicated in laboratory experiments. This contribution presents a methodology elaborated for performing ageing experiments in a hermetically sealed environment. Degradation of the material is evaluated through changes in the electrical tree inception voltage and test object capacitance over time. Securing the environmental isolation is accomplished with an isolation system consisting of a glass enclosure with attached metallic electrodes. Indium is used to create a glass-to-metal seal between the glass and the electrodes. The electrode geometry is of needle–plane type and the needle injection process is semi-automated to ensure specimen repeatability.

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Singh, I., i R. Narasimhan. "Notch sensitivity in nanoscale metallic glass specimens: Insights from continuum simulations". Journal of the Mechanics and Physics of Solids 86 (styczeń 2016): 53–69. http://dx.doi.org/10.1016/j.jmps.2015.10.001.

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Lu, Jun, i Guruswami Ravichandran. "Pressure-dependent flow behavior of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass". Journal of Materials Research 18, nr 9 (wrzesień 2003): 2039–49. http://dx.doi.org/10.1557/jmr.2003.0287.

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An experimental study of the inelastic deformation of bulk metallic glass Zr41.2Ti13.8Cu12.5Ni10Be22.5 under multiaxial compression using a confining sleeve technique is presented. In contrast to the catastrophic shear failure (brittle) in uniaxial compression, the metallic glass exhibited large inelastic deformation of more than 10% under confinement, demonstrating the nature of ductile deformation under constrained conditions in spite of the long-range disordered characteristic of the material. It was found that the metallic glass followed a pressure (p) dependent Tresca criterion τ = τ0 + βp, and the coefficient of the pressure dependence β was 0.17. Multiple parallel shear bands oriented at 45° to the loading direction were observed on the surfaces of the deformed specimens and were responsible for the overall inelastic deformation.

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Jutsell Nilsson, Douglas, i Stanislaw Gubanski. "Electrical detection of degradation in specimens of HVDC cable insulation". Proceedings of the Nordic Insulation Symposium, nr 26 (7.08.2019): 43–46. http://dx.doi.org/10.5324/nordis.v0i26.3276.

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One of the challenges in laboratory investigation of degradation and ageing of HVDC cable insulation is related to securing, or in other words, imitating the real service environment of the material specimens. So far, the published data refer to experiments conducted in thermo-oxidative conditions, which is not the case during normal cable operation. In reality the cable insulation is protected by a metallic barrier that blocks the transfer of any substances in and out of the construction. By-products from the cross-linking reactions cannot diffuse out and any foreign substances, such as oxygen and water, are blocked from entering into the insulation. Thus, in order to generate results that are valid, these conditions must be replicated in laboratory experiments.This contribution presents a methodology elaborated for performing ageing experiments in a hermetically sealed environment. Degradation of the material is evaluated through measurements of changes in the electrical tree inception voltage and test object capacitance over time. Securing the environmental isolation is primarily accomplished with an isolation system consisting of a glass enclosure with attached metallic electrodes. Indium is used to create a glass-to-metal seal between the glass and the electrodes. The electrode geometry is of needle-plane type and the needle injection process is semi-automated to secure a large degree of repeatability in specimen preparation.

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Phan, Thien Q., James P. Kelly, Michael E. Kassner, Veronica Eliasson, Olivia A. Graeve i Andrea M. Hodge. "Bulk Mechanical Properties Testing of Metallic Marginal Glass Formers". Journal of Metallurgy 2016 (18.08.2016): 1–8. http://dx.doi.org/10.1155/2016/6508597.

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We developed a unique three-point bend testing apparatus to measure bulk mechanical properties of a model metallic glass alloy (SAM2X5 with nominal composition Fe49.7Cr17.1Mn1.9Mo7.4W1.6B15.2C3.8Si2.4) prepared by spark plasma sintering. The relatively large sample sizes in the present work allowed for the preparation of test specimens with a macroscale cross section (in the millimeter range) with well-controlled sample dimensions closer to standardized tests. Wire saw cutting allowed for a relatively sharp notch radius (3x smaller than previous studies) and minimal sample damage. We determined that Young’s modulus and notch fracture toughness measured by our three-point bending apparatus are 230 GPa and 4.9 MPa·m1/2. Also, Vickers indentation and flexure testing provided consistent results for Young’s modulus. Indentation fracture toughness measured by Vickers indentation produced values at least 50% lower than by flexure. The microscale mechanical properties testing technique presented in this work and subsequent analyses are applicable to specimens of other compositions or ones prepared by other methods.

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Hu, Man Hong, i Yong Hu. "Effect of Cold Rolling on Thermal Stability of Zr₅₅ Al₁₀Ni₅Cu₃₀ Bulk Metallic Glass". Advanced Materials Research 239-242 (maj 2011): 490–95. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.490.

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The effect of cold rolling on thermal stability of bulk Zr55Al10Ni5Cu30metallic glass at room temperature had been investigated by means of X-ray diffractometer, high-resolution transmission electron microscope and differential scanning calorimeter. A number of the cold rolling processes were carried out to obtain different thickness reduction in specimens with the same original size. The XRD patterns of cold rolled specimens with thickness reduction up to 95% showed no clear difference with that of completely amorphous specimens. The relationship of the deformation with the thermal parameters of cold rolled specimen indicates that with the increase of thickness reduction, the glass transition temperature decreases obviously and the crystallization onset temperature and peak temperature decreases slightly. At the same time, the enthalpy of crystallization peak keeps almost constant during rolling. These results have revealed that cold rolling deformation has an apparently effect on the glass transition process but slightly effect on the crystallization process of Zr55Al10Ni5Cu30BMG.

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Boltynjuk, Evgeniy, Evgeniy Ubyivovk, Dmitriy Gunderov, Vladimir Mikhalovskii i Ruslan Z. Valiev. "Multiple Shear Bands in Zr-Based Bulk Metallic Glass Processed by Severe Plastic Deformation". Defect and Diffusion Forum 385 (lipiec 2018): 319–24. http://dx.doi.org/10.4028/www.scientific.net/ddf.385.319.

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The Zr62Cu22Al10Fe5Dy1 bulk metallic glass was subjected to high pressure torsion (HPT) processing at temperatures of 20 and 150°C. Structural studies were carried out by TEM on the lamella-sample prepared from the HPT-specimens in transversal direction to the specimen plane. TEM studies revealed formation of multiple shear bands with spacings in a 20-50 nm range for both HPT states. Shear bands could be divided in two types: primary and secondary bands. The morphology of shear bands strongly depends on the processing temperature. Shear bands are distributed homogeneously throughout the whole lamella-sample for state processed by HPT at temperature of 20°C. Regions with shear bands are divided by amorphous regions on lamella-sample cut from the sample processed by HPT at temperature of 150°C. Analysis of optical microscopy and SEM data showed that shear bands are distributed throughout the whole volume of HPT-specimens.

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Dutta, Tanmay, Ashish Chauniyal, I. Singh i R. Narasimhan. "Numerical investigation of tensile response of notched bulk metallic glass composite specimens". Modelling and Simulation in Materials Science and Engineering 28, nr 8 (16.10.2020): 085002. http://dx.doi.org/10.1088/1361-651x/abb98f.

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Chen, Y. M., T. Ohkubo, T. Mukai i K. Hono. "Structure of shear bands in Pd40Ni40P20 bulk metallic glass". Journal of Materials Research 24, nr 1 (styczeń 2009): 1–9. http://dx.doi.org/10.1557/jmr.2009.0001.

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The atomic structure of shear bands in Pd40Ni40P20 bulk metallic glass has been compared to an undeformed matrix phase using pair distribution functions (PDFs) derived from energy filtered nanobeam electron diffraction. Shear bands do not show any characteristic contrast in transmission electron microscopy (TEM) images when specimens are prepared with uniform thickness. PDFs from a shear band exhibit a slight decrease in the first peak, indicating a slight difference in packing density and short range order compared to the undeformed matrix.

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Luo, Yu, Leilei Xing, Yidong Jiang, Ruiwen Li, Chao Lu, Rongguang Zeng, Jinru Luo, Pengcheng Zhang i Wei Liu. "Additive Manufactured Large Zr-Based Bulk Metallic Glass Composites with Desired Deformation Ability and Corrosion Resistance". Materials 13, nr 3 (28.01.2020): 597. http://dx.doi.org/10.3390/ma13030597.

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Zr-based bulk metallic glasses have been attracting tremendous interest of researchers because of their unique combination of mechanical and chemical properties. However, their application is limited as large-scale production is difficult due to the limitation of cooling rate. Recently, additive manufacturing technology has been proposed as a new solution for fabricating bulk metallic glasses without size limitation. In this study, selective laser melting technology was used to prepare Zr60Fe10Cu20Al10 bulk metallic glass. The laser parameters for fabricating full dense amorphous specimens were investigated. The mechanical and corrosion resistance properties of the prepared samples were measured by micro-compression and electrochemical corrosion testing, respectively. Lastly, Zr60Fe10Cu20Al10 bulk metallic glass (BMG) with dispersed nano-crystals was made, and good deformation ability was revealed during micro-compression test. The corrosion resistance decreased a bit due to the crystalline phases. The results provide a promising route for manufacturing large and complex bulk metallic glasses with better mechanical property and acceptable corrosion resistance.

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Astanin, V. V., D. V. Gunderov i V. V. Titov. "Microhardness distribution over the surface of Zr-based metallic glass exposed to high-pressure torsion". Frontier materials & technologies, nr 3 (2022): 33–40. http://dx.doi.org/10.18323/2782-4039-2022-3-1-33-40.

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Identifying the peculiarities of the transformation of the structure and properties of bulk metallic glass (BMG) under high-pressure torsion (HPT) is of great interest. It is known that under HPT, the degree of deformation differs from the center to the edge of a disk which leads to the non-uniformity of the structure of obtained specimens. The change in microhardness value indicates the direction of change in BMG structure under the HPT, and the microhardness distribution indicates the HPT-specimen non-uniformity. The aim of the study is to identify the HPT influence on the microhardness value and microhardness distribution over the surface of specimens of amorphous alloys using an example of Vit105Zr-based BMG (Zr52.5Cu17.9Ni14.6Al10Ti5). The authors studied the distribution of microhardness over the surface of Vit105 Zr-based bulk metallic glass (BMG) in the initial state, in the state after HPT at n=1 and n=5 rotations, and after relaxing annealing. The study shows that the initial Vit105 BMG is characterized by a small spread in microhardness values, which indicates the material's high homogeneity. By reducing the excessive free volume, relaxing annealing increases microhardness without a significant increase in the spread of its values. HPT leads to a decrease in the zirconium BMG microhardness, which indicates an increase in the excessive free volume, but, at the same time, increases the uneven microhardness distribution over the specimen, while the microhardness values in one half of the HPT sample (n=1) are higher than in the other one. It demonstrates that BMG specimen deformation during HPT is related to the specific loading mechanisms.

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Hiremath, Anupama, i Joel Hemanth. "Experimental Evaluation of the Chill Casting Method for the Fabrication of LM-25 Aluminum Alloy-Borosilicate Glass (p) Composites". Key Engineering Materials 748 (sierpień 2017): 69–73. http://dx.doi.org/10.4028/www.scientific.net/kem.748.69.

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The paper investigates the novelty of application of end chills in fabricating Aluminum alloy metal matrix composites. An effort has also been made to evaluate the effect of chill material on the soundness of the castings obtained. The required composites were prepared using LM-25 Aluminum alloy as matrix material in which different weight percent of Borosilicate glass particles were added ranging from 3 wt.% to 12 wt.%. The variation in weight percent was brought about in steps of 3%. The fabrication of the composites was carried out in sand molds by incorporating two metallic (copper and Steel) and two non-metallic (Graphite and Silicon carbide) end chills. The specimens for strength and hardness tests were prepared as per ASTM standards and the specimens were drawn from near chill-end as well as from farther away from chill end. The microstructure of the specimens reveal a refined grain structure proving the sound quality of the castings. The result analysis also leads to the conclusion that metallic chills are more beneficial as compared to non-metallic chills for obtaining a good quality composites. Copper chill with a high volumetric heat capacity proved to be the best chill material amongst the others.

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Li, Jing, X. Gu i T. C. Hufnagel. "Using Fluctuation Microscopy to Characterize Structural Order in Metallic Glasses". Microscopy and Microanalysis 9, nr 6 (21.11.2003): 509–15. http://dx.doi.org/10.1017/s1431927603030459.

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We have used fluctuation microscopy to reveal the presence of structural order on length scales of 1–2 nm in metallic glasses. We compare results of fluctuation microscopy measurements with high resolution transmission electron microscopy and electron diffraction observations on a series of metallic glass samples with differing degrees of structural order. The agreement between the fluctuation microscopy results and those of the other techniques is good. In particular, we show that the technique used to make thin specimens for electron microscopy affects the structure of the metallic glass, with ion thinning inducing more structural order than electropolishing. We also show that relatively minor changes in the composition of the alloy can have a significant effect on the medium-range order; this increased order is correlated with changes in mechanical behavior.

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Lu, Xiaoyang, Mussokulov Nursulton, Yulei Du i Wenhe Liao. "Structural and Mechanical Characteristics of Cu50Zr43Al7 Bulk Metallic Glass Fabricated by Selective Laser Melting". Materials 12, nr 5 (6.03.2019): 775. http://dx.doi.org/10.3390/ma12050775.

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In this work, the structural and mechanical characteristics of Cu50Zr43Al7 bulk metallic glass (BMG) fabricated by selective laser melting (SLM) are studied and the impacts from the SLM process are clarified. Cu50Zr43Al7 alloy specimens were manufactured by the SLM method from corresponding gas-atomized amorphous powders. The as-built specimens were examined in terms of phase structure, morphologies, thermal properties and mechanical behavior. The x-ray diffraction and differential scanning calorimetry results showed that structural relaxation and partial crystallization co-exist in the as-fabricated Cu50Zr43Al7 glassy samples. The nano- and micro- hardness and the elastic modulus of the SLM-fabricated Cu50Zr43Al7 BMG were higher than CuZrAl ternary BMGs with similar compositions prepared by conventional mold casting, which can be attributed to the structural relaxation in the former sample. However, the macro compressive strength of the SLM-fabricated Cu50Zr43Al7 BMG was only 1044 MPa mainly due to its porosity. This work suggests that the SLM process induced changes in structural and mechanical properties are significant and cannot be neglected in the fabrication of BMGs.

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Sharma, Ankush P., Sanan H. Khan i Venkitanarayanan Parameswaran. "Response and failure of fiber metal laminates subjected to high strain rate tensile loading". Journal of Composite Materials 53, nr 11 (11.10.2018): 1489–506. http://dx.doi.org/10.1177/0021998318804620.

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The tensile behavior of fiber metal laminates consisting of layers of aluminum 2024-T3 alloy and glass fiber reinforced composites under high strain rate loading is investigated. Fiber metal laminates having four different layups, but all having the same total metal layer thickness, were fabricated using a combined hand lay-up cum vacuum bagging method. The fiber metal laminate specimens were loaded in high strain rate tension using a split Hopkinson tensile bar. The rate-dependent behavior of the glass fiber composite was also obtained as baseline data. The strain on the gage area of the specimen was measured directly using high-speed digital image correlation. Another high-speed camera was used to capture the sequence of damage by viewing the specimen edgewise. The results indicated that the strength of the fiber metal laminates increased at high strain rates primarily due to the rate-dependent behavior of the composite used. The response was also influenced by the distribution of the metallic layers in the fiber metal laminates. The failure in the case where the individual composite layers were separated by metallic layers was more progressive in nature.

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Ramya Devi, G., i K. Palanikumar. "Tensile Property Evaluation of Woven Glass Fiber Reinforced Plastic and Aluminium Stack". Applied Mechanics and Materials 766-767 (czerwiec 2015): 44–49. http://dx.doi.org/10.4028/www.scientific.net/amm.766-767.44.

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The desire of weight reduction and improved damage tolerance characteristics of the aircraft structures throws a light on the development on Fiber Metal Laminates (FML), one of the hybrid composites, with the combination of metallic and non-metallic layers. In this study, laminates of alternating layers of aluminium (metal) and glass fibers with Woven Roving mat is fabricated. Tensile test based on ASTM standard are then conducted on the laminates to study their yield properties. The interfacial bonding between the layers are analyzed using the Scanning Electron Microscopy of tested specimens.

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Das, J., S. Pauly, C. Duhamel, B. C. Wei i J. Eckert. "Microstructure and mechanical properties of slowly cooled Cu47.5Zr47.5Al5". Journal of Materials Research 22, nr 2 (luty 2007): 326–33. http://dx.doi.org/10.1557/jmr.2007.0033.

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Cu47.5Zr47.5Al5 was prepared by arc melting and solidified in situ by suction casting into 2–5-mm-diameter rods under various cooling rates (200–2000 K/s). The microstructure was investigated along the length of the rods by electron microscopy, differential scanning calorimetry and mechanical properties were investigated under compression. The microstructure of differently prepared specimens consists of macroscopic spherical shape chemically inhomogeneous regions together with a low volume fraction of randomly distributed CuZr B2 phase embedded in a 2–7 nm size clustered “glassy-martensite” matrix. The as-cast specimens show high yield strength (1721 MPa), pronounced work-hardening behavior up to 2116 MPa and large fracture strain up to 12.1–15.1%. The fracture strain decreases with increasing casting diameter. The presence of chemical inhomogenities and nanoscale “glassy-martensite” features are beneficial for improving the inherent ductility of the metallic glass.

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Roy, S., A. Chatterjee i D. Chakravorty. "Glass-metal nanocomposites in bulk form by sol-gel route followed by hot pressing". Journal of Materials Research 8, nr 4 (kwiecień 1993): 689–92. http://dx.doi.org/10.1557/jmr.1993.0689.

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Glass-metal nanocomposites involving copper and nickel, respectively, have been synthesized in bulk form by hot pressing sol-gel derived silica-metal nanoparticle composite powders. The particle diameters range from 9 to 17.5 nm. The specimens exhibit the characteristic behavior of the metallic species in their nanocrystalline forms.

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Kosiba, Konrad, Liang Deng i Sergio Scudino. "Viscous Flow of Supercooled Liquid in a Zr-Based Bulk Metallic Glass Synthesized by Additive Manufacturing". Materials 13, nr 17 (28.08.2020): 3803. http://dx.doi.org/10.3390/ma13173803.

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The constraint in sample size imposed by the critical cooling rate necessary for glass formation using conventional casting techniques is possibly the most critical limitation for the extensive use of bulk metallic glasses (BMGs) in structural applications. This drawback has been recently overcome by processing glass-forming systems via additive manufacturing, finally enabling the synthesis of BMGs with no size limitation. Although processing by additive manufacturing allows fabricating BMG objects with virtually no shape limitation, thermoplastic forming of additively manufactured BMGs may be necessary for materials optimization. Thermoplastic forming of BMGs is carried out above the glass transition temperature, where these materials behave as highly viscous liquids; the analysis of the viscosity is thus of primary importance. In this work, the temperature dependence of viscosity of the Zr52.5Cu17.9Ni14.6Al10Ti5 metallic glass fabricated by casting and laser powder bed fusion (LPBF) is investigated. We observed minor differences in the viscous flow of the specimens fabricated by the different techniques that can be ascribed to the higher porosity of the LPBF metallic glass. Nevertheless, the present results reveal a similar overall variation of viscosity in the cast and LPBF materials, which offers the opportunity to shape additively manufactured BMGs using already developed thermoplastic forming techniques.

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35

Michalik, Štefan, Zuzana Molčanová, Michaela Šulíková, Katarína Kušnírová, Pál Jóvári, Jacques Darpentigny i Karel Saksl. "Structure and Physical Properties of Mg93−xZnxCa7 Metallic Glasses". Materials 16, nr 6 (14.03.2023): 2313. http://dx.doi.org/10.3390/ma16062313.

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The Mg-Zn-Ca system has previously been proposed as the most suitable biodegradable candidate for biomedical applications. In this work, a series of ribbon specimens was fabricated using a melt-spinning technique to explore the glass-forming ability of the Mg-Zn-Ca system along the concentration line of 7 at.% of calcium. A glassy state is confirmed for Mg50Zn43Ca7, Mg60Zn33Ca7, and Mg70Zn23Ca7. Those samples were characterised by standard methods to determine their mass density, hardness, elastic modulus, and crystallisation temperatures during devitrification. Their amorphous structure is described by means of pair distribution functions obtained by high-energy X-ray and neutron diffraction (HEXRD and ND) measurements performed at large-scale facilities. The contributions of pairs Mg-Mg, Mg-Zn, and Zn-Zn were identified. In addition, a transformation process from an amorphous to crystalline structure is followed in situ by HEXRD for Mg60Zn33Ca7 and Mg50Zn43Ca7. Intermetallic compounds IM1 and IM3 and hcp-Mg phase are proposed to be formed in multiple crystallisation eventss.

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Li, Hongqi, Li Li, Cang Fan, Hahn Choo i Peter K. Liaw. "Nanocrystalline coating enhanced ductility in a Zr-based bulk metallic glass". Journal of Materials Research 22, nr 2 (luty 2007): 508–13. http://dx.doi.org/10.1557/jmr.2007.0060.

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Compression tests were conducted on the as-cast Zr58Ni13.6Cu18Al10.4 metallic glass at room temperature. The effect of nanocrystalline Ni-15%Fe coating (mean grain size: ∼10 nm) on mechanical properties was investigated. The results demonstrate that the strength, elastic limit, Young’s modulus, and fracture geometry and morphology are not affected by this nanostructured coating. However, the compressive plastic strain increased noticeably when the specimens were coated with a layer of nanocrystal, which is attributed to the increased shear band density. The high shear band density is suggested to be due to the inhibition of shear band operation by nanocrystalline coating. The significance of this study is that a new strategy was developed to improve the ductility of bulk metallic glasses.

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37

Lakshmanan, V., i J. C. M. Li. "Magnetic domains around annealed shear bands and embrittlement of FeBSi metallic glass". Journal of Materials Research 6, nr 2 (luty 1991): 371–75. http://dx.doi.org/10.1557/jmr.1991.0371.

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Magnetic domains in the vicinity of shear bands produced by bending were investigated to study the effect of furnace annealing on the domain structures. Domain wall spacings were measured as a function of annealing time at several temperatures. The same specimens were also used to evaluate the degree of embrittlement by measuring the bending fracture strains.

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Zameer, Syed, i Mohamed Haneef. "Mechanical and Tribological Behavior of Bio Polymer Matrix Composites for Biomedical Prosthesis Applications". Advanced Materials Research 1105 (maj 2015): 7–12. http://dx.doi.org/10.4028/www.scientific.net/amr.1105.7.

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Due to limitations of Conventional metallic biomaterials an attempt is made to develop a new hybrid polymer matrix composite for load bearing applications of Hip joints in the human body. Ultra high molecular weight polyethylene matrix material was blended with 50 wt% of short E-glass fibres and TiO2particles with varying percentage of reinforcement, using injection moulding machine. Fabricated composites specimens were subjected to tensile strength test, Fatigue test, SEM, Wear analysis test and In vivo Biocompatibility test to evaluate mechanical and tribological properties, required for bone joints load bearing applications. The maximum tensile strength of 41.5 MPa and young’s modulus of 7.5 GPa is obtained. The behavior of S-N curve obtained after the test is linear in nature, which leads to failure at 105cycles for the fabricated composite specimen. Also it reveals that fracture is due to brittle failure. The wear mechanism of composite specimen is, because of abrasion. Density of composite specimens was increased after dipping in the simulated body fluid solution.

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Vianco, P. T., i J. C. M. Li. "Effect of tensile stress on the annealed structure of a metallic glass". Journal of Materials Research 2, nr 4 (sierpień 1987): 461–70. http://dx.doi.org/10.1557/jmr.1987.0461.

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The low-temperature (120°–245°C) structural relaxation of Metglas¯ 2826B (Ni49Fe29P14B6Si2) amorphous alloy was investigated for samples subjected to a tensile stress in the range of 20–400 MPa during annealing. The stress-annealed samples demonstrated a much smaller increase of microhardness than was observed in similarly annealed ribbons without a stress. Further heat treatment of the stress-annealed specimens, this time without the stress, was capable of increasing the microhardnesses of only some ribbons to values equal to those of samples similarly heat treated initially without a stress. An additional exothermic peak in the differential scanning calorimetry (DSC) thermograms of the stress-annealed specimens indicated the presence of a more disordered structure at room temperature, which was found to correlate with the lower microhardness values. Otherwise, those artifacts of the DSC thermograms that were characteristic of samples annealed without a stress were still present in the stress-annealed ribbons. No effect on the crystallization temperature was noted but the glass transition temperature was increased in the stress-annealed case with respect to values attained when the stress was absent during heat treatment. A reduction in the degree of embrittlement of those samples annealed with a tensile stress was a further indication of more disorder in the stress-annealed ribbons.

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Jagdale, Shweta, Akib Jabed, Sumanth Theeda, Chandra Sekhar Meduri, Zhonglue Hu, Molla Hasan i Golden Kumar. "Review of Thermoplastic Drawing with Bulk Metallic Glasses". Metals 12, nr 3 (18.03.2022): 518. http://dx.doi.org/10.3390/met12030518.

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This study summarizes the recent progress in thermoplastic drawing of bulk metallic glasses. The integration of drawing with templated embossing enables the fabrication of arrays of high-aspect-ratio nanostructures whereas the earlier drawing methodologies are limited to a single fiber. The two-step drawing can produce metallic glass structures such as, vertically aligned nanowires on substrates, nanoscale tensile specimens, hollow microneedles, helical shafts, and micro-yarns, which are challenging to fabricate with other thermoplastic forming operations. These geometries will open new applications for bulk metallic glasses in the areas of sensors, optical absorption, transdermal drug-delivery, and high-throughput characterization of size-effects. In this article, we review the emergence of template-based thermoplastic drawing in bulk metallic glasses. The review focuses on the development of experimental set-up, the quantitative description of drawing process, and the versatility of drawing methodology.

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Mortazavian, Seyyedvahid, i Ali Fatemi. "Notch Effects on Fatigue Behavior of Thermoplastics". Advanced Materials Research 891-892 (marzec 2014): 1403–9. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1403.

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An experimental study was conducted to evaluate notch effects on fatigue behavior of a neat polymer (PP impact co-polymer) and a composite made of 30 wt% short glass fibers in polybutylene terephthalate (PBT). A plate-type specimen geometry with a central circular hole was used. The experiments were conducted at room temperature in uniaxial tension-tension (R = 0.1) and tension-compression (R = -1) loading conditions. Some analytical methods including Neubers rule and the method of critical distances were used in addition to FEA to predict fatigue life of notched specimens. Neubers rule commonly used for metallic materials proved to be an accurate method for predicting the notched fatigue life of the thermoplastics considered.

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Dutta, Tanmay, Ashish Chauniyal, I. Singh, R. Narasimhan, P. Thamburaja i U. Ramamurty. "Plastic deformation and failure mechanisms in nano-scale notched metallic glass specimens under tensile loading". Journal of the Mechanics and Physics of Solids 111 (luty 2018): 393–413. http://dx.doi.org/10.1016/j.jmps.2017.11.011.

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Shin, Hyung Seop, Ki Hyun Kim, Young Jin Jung i Dong Kyun Ko. "Impact Fracture Behavior of Zr-Based Bulk Metallic Glass Using Subsize Charpy Specimen". Key Engineering Materials 297-300 (listopad 2005): 1356–64. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.1356.

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The impact fracture behavior of Zr-based bulk metallic glass was investigated by an instrumented impact tester using subsize Charpy specimens. Influences of loading rate and notch shape on the fracture behavior of amorphous Zr-Al-Ni-Cu alloy were examined. As a result, the maximum load and absorbed fracture energy under impact loading were lower than those under quasi-static loading. A large part of the absorbed fracture energy in the Zr-based BMG was consumed in the process for crack initiation and not for crack propagation. In addition, fractographic characteristics of BMGs were investigated. Fractured surfaces under impact loading are smoother than those under quasi-static loading. The absorbed fracture energy appeared differently depending on the appearance of the shear bands developed. It can be found that the fracture energy and fracture toughness of Zr-based BMG are closely related with the extent of shear bands developed during fracture.

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44

Jiang, W. H., F. X. Liu, D. C. Qiao, H. Choo i P. K. Liaw. "Plastic flow in dynamic compression of a Zr-based bulk metallic glass". Journal of Materials Research 21, nr 6 (1.06.2006): 1570–75. http://dx.doi.org/10.1557/jmr.2006.0194.

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Using geometrically constrained specimens, the plastic flow behaviors of the as-cast and the relaxed Zr52.5Cu17.9Ni14.6Al10.0Ti5.0 bulk metallic glass in the dynamic compression were investigated. Both alloys exhibit a significant plasticity in the dynamic compression. The plastic deformation in both alloys is still inhomogeneous, which is characterized by the serrated plastic flow and the formation of shear bands. Free volumes affect the shear banding and the plastic flow. The reduced free volume results in the deviation of the shear banding direction from the maximum shear stress. The relaxed alloy exhibits the obvious stress overshoot, which is consistent with the theoretical prediction using a free volume model.

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Cuc, Stanca, Alexandru Burde, Cosmin Cosma, Dan Leordean, Mircea Rusu, Nicolae Balc, Doina Prodan, Marioara Moldovan i Razvan Ene. "Adhesion between Biocomposites and Different Metallic Structures Additive Manufactured". Coatings 11, nr 4 (20.04.2021): 483. http://dx.doi.org/10.3390/coatings11040483.

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This study was concerned with the adhesion of resin cement to metal surfaces obtained by selective laser melting process (SLM), and how it could be improved the bond strength at the biocomposite-metal junction. The SLM substrates were manufactured out of pure titanium (Ti), Ti6Al7Nb, and CoCr alloys. The metallic surfaces were covered with 5 types of biocomposites: 2 commercially resin-modified glass-ionomer cements (GC Fuji Plus and KETAC CEM) and 3 types of in-house developed materials. These biocomposites were mechanical characterized under compression and bending trials. The biocomposites-metal adhesion was settled both on as built metallic surfaces and after they were sandblasted with alumina. All the sandblasted SLM surfaces presented higher adhesion strength in comparison with the untreated specimens. The CoCr specimens show the highest bonding value. Additionally, the morphological aspects of joining interfaces were investigated using a scanning electron microscope (SEM). The mechanical properties and metal adhesion of these biocomposites were influenced by the liquid powder ratio. It is essential to apply a surface treatment on SLM substrate to achieve a stronger bond. Also, the chemical composition of biocomposite is a major factor which may improve the adhesion of it on different metallic substrates.

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Laakkonen, Markus, Theo J. Rickert i Lasse Suominen. "Stress Measurements in Glass and Plastic by Optical Hole-Drilling". Materials Science Forum 768-769 (wrzesień 2013): 95–100. http://dx.doi.org/10.4028/www.scientific.net/msf.768-769.95.

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Quantitative residual stress depth profile measurements are common in metallic parts but not in glass or plastic. This paper describes some experimental stress depth profile measurements using hole-drilling with electronic speckle pattern interferometry (ESPI) in two types of glasses and two thermoplastics. Stress depth profiles in laminated and toughened glass specimens show the expected low stresses in the former and significant compressive stresses near the surface in the latter for the as-is condition. The stress curves shift towards tensile stresses during slight bending deformation, as expected. The bending devices initially used for experiments with Bayblend® and Makrolon® were deforming the specimens too severely to allow proper, static, measurements. Significant stress reductions due to creep were measured for extended bending times. Subsequent measurements for less severe bending show similar stress curve characteristics. Residual stresses in the as-is condition apparently account for some of the differences to the predicted bending stress profile.

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SHIN, HYUNG-SEOP, KI-HYUN KIM i SANG-YEOB OH. "FRACTURE BEHAVIOR OF Zr-BASED BULK METALLIC GLASS UNDER IMPACT LOADING". International Journal of Modern Physics B 20, nr 25n27 (30.10.2006): 4359–64. http://dx.doi.org/10.1142/s0217979206041355.

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The fracture behavior of a Zr -based bulk amorphous metal under impact loading using subsize V-shaped Charpy specimens was investigated. Influences of loading rate on the fracture behavior of amorphous Zr - Al - Ni - Cu alloy were examined. As a result, the maximum load and absorbed fracture energy under impact loading were lower than those under quasi-static loading. A large part of the absorbed fracture energy in the Zr -based BMG was consumed in the process for crack initiation and not for crack propagation. In addition, fractographic characteristics of BMGs, especially the initiation and development of shear bands at the notch tip were investigated. Fractured surfaces under impact loading are smoother than those under quasi-static loading. The absorbed fracture energy appeared differently depending on the appearance of the shear bands developed. It can be found that the fracture energy and fracture toughness of Zr -based BMG are closely related with the extent of shear bands developed during fracture.

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Giannuzzi, Lucille A., Richard Young i Pete Carleson. "Using a Focused Ion Beam (FIB) System to Extract TEM-Ready Samples from Complex Metallic and Ceramic Structures". Microscopy Today 7, nr 2 (marzec 1999): 12–15. http://dx.doi.org/10.1017/s1551929500063860.

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AbstractDriven by the analytical needs of microelectronics, magnetic media and micro-fabrication industries, focused ion beam (FIB) systems are now capable of milling and manipulating samples for the analysis of microstructure features having dimensions of 180 nm or less, A technique for locating and extracting site specific specimens for examination by transmission electron microscopy (TEM) has been developed. An identified feature can be located and precisely milled with an FIB system from two sides to prepare an ultrathin sample, and then extracted from the region with a glass rod micromanipulator onto a grid for TEM analysis. This specimen preparation method has been applied to semiconductor failure analysis and to the study of metallic and ceramic microsiructures with irregular topographies and complex mufti-layered components.

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Krus, Tyler D., Thomas F. Juliano, Laszlo J. Kecskes i Mark R. VanLandingham. "Initial plasticity onset in Zr- and Hf-rich bulk metallic glasses during instrumented indentation". Journal of Materials Research 22, nr 5 (maj 2007): 1265–69. http://dx.doi.org/10.1557/jmr.2007.0185.

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Sudden jumps in nanoindentation load-displacement curves of bulk metallic glasses (BMGs) signify the onset of plastic deformation. These events are investigated on varying compositions of Zr- and Hf-rich BMGs. Load-versus-displacement graphs for spherical indentations are analyzed to determine displacement, load, intensity of deformation, energy per volume, energy loss, and pressure corresponding to these key locations. Attention is focused on pressure, energy loss, and energy per volume at initial plasticity in response to varying strain rates, indenter tip radii, preload, and material composition. Energy loss was found to correlate with preload. The Zr-rich metallic glass was found to plastically deform in response to smaller loads than Hf-rich specimens.

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Gunti, Abhilash, Parijat Pallab Jana, Min-Ha Lee i Jayanta Das. "Effect of Cold Rolling on the Evolution of Shear Bands and Nanoindentation Hardness in Zr41.2Ti13.8Cu12.5Ni10Be22.5 Bulk Metallic Glass". Nanomaterials 11, nr 7 (25.06.2021): 1670. http://dx.doi.org/10.3390/nano11071670.

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The effect of cold rolling on the evolution of hardness (H) and Young’s modulus (E) on the rolling-width (RW), normal-rolling (NR), and normal-width (NW) planes in Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vitreloy 1) bulk metallic glass (BMG) was investigated systematically using nanoindentation at peak loads in the range of 50 mN–500 mN. The hardness at specimen surface varied with cold rolling percentage (%) and the variation is similar on RW and NR planes at all the different peak loads, whereas the same is insignificant for the core region of the specimen on the NW plane. Three-dimensional (3D) optical surface profilometry studies on the NR plane suggest that the shear band spacing decreases and shear band offset height increases with the increase of cold rolling extent. Meanwhile, the number of the pop-in events during loading for all the planes reduces with the increase of cold rolling extent pointing to more homogeneous deformation upon rolling. Calorimetric studies were performed to correlate the net free volume content and hardness in the differently cold rolled specimens.

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