Spherical indentation response of metallic glasses

Patnaik, Minati; Narasimhan, R.; Ramamurty, Upadrasta

doi:10.1016/j.actamat.2004.03.028

Cited by 149 publications

(94 citation statements)

References 23 publications

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“…As seen in Fig. 2, the curve from D-P criterion prediction is close to that by the M-C criterion in most regime of the normal stress, which explains why both criteria can capture the deformation of metallic glasses in certain boundary-value problems [21][22][23][24]. The D-P and M-C values are very consistent with Lewandowiski's report [3] using superimposed method.…”

Section: Resultssupporting

confidence: 79%

“…We hence use the term ''failure" instead of ''yielding" to describe the critical combinations of shear and normal stress which trigger fracture in Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 . It is noted that there could be possibilities when shear banding does not lead to catastrophic failure, for example in bending tests [37] and in indentation experiments [21][22][23][24]. In those states of stress, ''yielding" apparently differs from ''failure".…”

Section: Resultsmentioning

confidence: 99%

“…Both parameters could be determined from experiments. As D-P criterion was also applied to the deformation of metallic glasses to capture its pressure dependent failure and plastic flow behavior [22][23][24]. We present the predictions by the D-P criterion with A = 1.066 ± 0.018 GPa and B = À0.016 ± 0.008 from the least square fitting using Eq.…”

Section: Resultsmentioning

confidence: 99%

“…Instrumented indentation and finite element simulations have also been employed to examine the pressure sensitivity of strength in BMGs [21][22][23][24] and they all suggested that pressure sensitive M-C or D-P [25] were better suited to capture deformation in structures with complex stress state. Finite-element modeling with embedded M-C criterion is able to captured typical features seen from systematic experimental characterizations of BMGs [26].…”

Section: Introductionmentioning

confidence: 99%

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Spiral fracture in metallic glasses and its correlation with failure criterion

Lei

Wei

2015

Acta Materialia

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a b s t r a c tWe report the observation of spiral fracture of the metallic glass Zr 41 Ti 14 Cu 12.5 Ni 10 Be 22.5 (at.%) subjected to both shear and normal stresses. The spiral angle (that between the spiral line and the loading axis) increases as we gradually change the normal stress from tensile (positive) to compressive (negative). The spiral nature of the fractured surface leads to a left-handed helix fractography pattern in tension, and a right-handed helix in compression. The Mohr-Coulomb type of failure is essential for the unique spiral fracture. The use of spiral angles resulted from torsion-tension experiments provide another novel experimental strategy to examine the failure criterion as well as stress state dependence of deformation mechanisms which lead to failure in metallic glasses.

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Section: Resultssupporting

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spiral fracture in metallic glasses and its correlation with failure criterion

Lei

Wei

2015

Acta Materialia

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“…However, very little is known about this phenomenon for cohesive-frictional materials. Giannakopoulos and Larsson [6] and Vaidyanathan et al [7] studied the pyramidal indentation of cohesive-frictional materials using the finite element method and, more recently, Narasimhan [8] and Patnaik et al [9] analysed the applicability of the expanding cavity model [10,11] to studying the conical and spherical indentation response of elasto-plastic materials in which the flow stress depends on the hydrostatic pressure. However, none of these studies focused on the determination of the constitutive response of the material from the indentation curve, and there is no reliable methodology for estimating the yield stress and pressure sensitivity in amorphous materials from instrumented indentation.…”

Section: Introductionmentioning

confidence: 99%

Determination of the mechanical properties of amorphous materials through instrumented nanoindentation

et al. 2012

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A novel methodology based on instrumented indentation is developed to determine the mechanical properties of amorphous materials which present cohesive-frictional behaviour. The approach is based on the concept of a universal hardness equation, which results from the assumption of a characteristic indentation pressure proportional to the hardness. The actual universal hardness equation is obtained from a detailed finite element analysis of the process of sharp indentation for a very wide range of material properties, and the inverse problem (i.e. how to extract the elastic modulus, the compressive yield strength and the friction angle) from instrumented indentation is solved. The applicability and limitations of the novel approach are highlighted. Finally, the model is validated against experimental data in metallic and ceramic glasses as well as polymers, covering a wide range of amorphous materials in terms of elastic modulus, yield strength and friction angle.

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Observation of Instabilities during Plastic Deformation by in‐situ SEM Indentation Experiments

et al. 2005

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The plastic deformation behaviour of materials has great significance for metal forming processes as well as for safety in structural design. A detailed understanding of instabilities during plastic deformations and of the underlying mechanisms is of great importance for the design of materials with stable plastic deformation and high ductility. We here present first results on the observation of pop-ins and shear band formation during indentation in a Zr-based bulk metallic glass (Vitreloy-105) with the nominal composition Zr 52.5 Cu 17.9 Ni 14.6 Al 10 Ti 5 . We concentrate thereby on observations from in-situ scanning electron microscopy (SEM) experiments using a recently developed miniaturized instrumented indentation system that can be used inside the SEM chamber. We found, for the first time, a partial correlation between displacement bursts in the load-displacement curve and shear band activity at the specimen surface. Frames from video sequences with the respective load displacement curve are presented as evidence.Metallic glasses are known for over 40 years now. Klement et al. have prepared the first metallic glass in the year 1960. [1] The glass forming process in these metals required cooling rates in the range of 10 6 Ks ±1 , which could not be reached in bulk materials. Therefore, and despite attractive mechanical properties, structural applications were not possible. New and better glass forming compositions have been found since and the necessary cooling rates have dropped considerably to reach 1 Ks ±1 today and components several mm thick can now be cast routinely. [2] The high hardness, good wear and corrosion resistance and a toughness greater than ceramics make bulk metallic glasses (BMGs) attractive materials for structural applications. [3] However, plastic deformation of BMGs is highly unstable and their ductility, particularly in tension, is very limited. [4±9] Plastic deformation is highly localized inside shear bands. In tension, ductility is often so low that only a single dominant shear band develops, which leads to specimen failure. However, extensive shear banding can be observed in compression, bending or indentation tests. A thorough understanding of the plastic deformation is necessary in order to increase tensile ductility in these materials.

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Spherical indentation response of metallic glasses

Cited by 149 publications

References 23 publications

Spiral fracture in metallic glasses and its correlation with failure criterion

Spiral fracture in metallic glasses and its correlation with failure criterion

Determination of the mechanical properties of amorphous materials through instrumented nanoindentation

Observation of Instabilities during Plastic Deformation by in‐situ SEM Indentation Experiments

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