Rate Dependence of Serrated Flow During Nanoindentation of a Bulk Metallic Glass

Schuh, Christopher A.; Nieh, T.G.; Kawamura, Yoshihito

doi:10.1557/jmr.2002.0243

Cited by 163 publications

(113 citation statements)

References 23 publications

(35 reference statements)

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“…Similar observations were also reported for glass [21][22][23][24], polycrystalline alumina [25,26,43,44], bulk metallic glasses [27][28][29], sapphire [30], GaN [31], and ZnO [32].…”

Section: Resultssupporting

confidence: 87%

“…The occurrence of the pop-in behaviour was also reported for glass [21][22][23][24], polycrystalline alumina [25,26,43,44], bulk metallic glass [27][28][29], sapphire [30], GaN [31], and ZnO [32]. The occurrence of pop-in has often been associated with shear localization [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 85%

“…The effect of these deformations are revealed by the occurrence of "multiple micro-pop-in" and "multiple micropop-out" events in the load-depth plots, followed by the formation of shear deformation bands and localized microcracking in and around the indentation cavity [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] and the formation of dislocation loops in the alumina sample. The detailed mechanisms of pop-in events which occur during indentation in ceramics are far from being well understood and may be strongly sensitive to the plane bearing the nanoindentation, nanoindenter tip radius, temperature and so forth, while the microscale hardness may [38][39][40][41] or may not be [42] sensitive to strain and loading rate variation.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Contact Deformation of Alumina

Bhattacharya

Mukhopadhyay

2012

ISRN Ceramics

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The study of contact-induced deformations during hardness evaluation and the subsequent damage mechanisms of alumina under low loads deserves significant importance for its applications as wear-resistant inserts, biomedical implants, thin films, and armour plates, because the contact-induced brittle failure is an issue of major scientific concern that prevents their widespread commercial applications. However, the studies on hardness of dense, coarse grain alumina at ultralow load, for example, 1 N, are still lacking. Therefore, the present study was conducted on a dense (∼95% of theoretical) coarse-grain (∼20 μm) alumina at a low peak load of 1 N with varying loading rates (10 −3 -10 0 N·s −1 ) applied in depth sensitive indentation experiments. The results showed profuse presence of multiple micro-pop-in and pop-out events possibly linked to dislocation nucleations underneath the indenter. The critical resolved shear stress (τ CRSS ) was found to enhance with the increase in applied loading rates. The occurrences of the localized shear deformation band formation and microcracking in and around the indentation cavity were explained in terms of the correlation between the nanoscale plasticity events, the small magnitude of (τ CRSS ), the maximum shear stress (τ max ) developed just underneath the indenter, and the dislocation loop radius (R d ).

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“…Similar observations were also reported for glass [21][22][23][24], polycrystalline alumina [25,26,43,44], bulk metallic glasses [27][28][29], sapphire [30], GaN [31], and ZnO [32].…”

Section: Resultssupporting

confidence: 87%

Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Contact Deformation of Alumina

Bhattacharya

Mukhopadhyay

2012

ISRN Ceramics

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“…Figure 18 shows, for instance, typical load-depth (F-h) curves obtained for four different loading rates in the range of 0.6-20mN/s on Pd-40Ni-20P (at.%) bulk metallic glass. 81 At low loading rates (generally under 10 mN/s), the steps in the loading curve can clearly be observed. In the indentation curve, the displacements, ⌬D p , occurring in the bursts also increase linearly with the increase of the penetration depth, h. 65 As the loading rate increases, the stair-step-like P-h curves become smooth parabolic curves.…”

Section: Plastic Instabilities-serrated Flow-in Bulk Metallic Glamentioning

confidence: 96%

Depth-sensing indentation tests in studying plastic instabilities

et al. 2004

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This review surveys the phenomenon of plastic instabilities occurring in depth-sensing indentation measurements. Investigations presented focus on the characterization of Portevin-Le Châtelier type instabilities observed in different metal alloys during indentation. The effect of some important factors such as solute concentration, the formation of Guinier-Preston zones, and grain size and orientation are described and discussed. The phenomenon of plastic instabilities as serrated flow recently observed in bulk metallic glasses is also briefly reviewed. I. GENERAL APPLICATIONS OF DEPTH-SENSING INDENTATION METHODIn the last two decades, depth-sensing indentation (DSI) became widely used for the mechanical characterization of solids. The reason for its popularity is that DSI enables the determination of mechanical properties even for a small volume of material without complicated sample preparation. The DSI method is an improvement over conventional hardness measurement. The most important motivations of this development are the following: (i) the optical evaluation of extremely small indentations in hard materials and thin layers is very uncertain, (ii) the DSI enables the measurement of the depth profile of the hardness perpendicular to the surface in gradient materials, (iii) the method allows the study of changes in the hardness during deformation under load (dynamic hardness), and (iv) the penetration or the loading rate, which affect the hardness value, can be selected and controlled during indentation.During the DSI process, an indenter is penetrated into the surface of the material with constant indentation rate or loading rate. In the majority of the measurements, the loading rate is held constant. When the load reaches its selected maximum value, the load decreases with the same rate as for loading and the indenter moves backward. The load-penetration depth curves are recorded in both the loading and the unloading parts of the measurement as schematically shown in Fig.

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“…In compression, BMG exhibits essentially no strain hardening, and plastic flow is serrated with many small load drops that correspond to the activation of individual shear bands. Wight et al [19], Golovin et al [20] and Schuh et al [21] studied the serrated flow in BMG using nanoindentation. The result was shown to depend strongly on the indentation strain rate, with lower rates promoting more prominent serrations or displacement bursts.…”

Section: Introductionmentioning

confidence: 99%

Strain rate-dependent compressive deformation behavior of Nd-based bulk metallic glass

et al. 2005

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Compressive deformation behavior of the Nd 60 Fe 20 Co 10 Al 10 bulk metallic glass was characterized over a wide strain rate range (6.0!10 K4 to 1.0!10 3 s K1 ) at room temperature. Fracture stress was found to increase and fracture strain decrease with increasing applied strain rate. Serrated flow and a large number of shear bands were observed at the quasi-static strain rate (6.0!10 K4 s K1 ). The results suggest that the appearance of a large number of shear bands is probably associated with flow serration observed during compression; and both shear banding and flow serration are a strain accommodation and stress relaxation process. At dynamic strain rates (1.0!10 3 s K1 ), the rate of shear band nucleation is not sufficient to accommodate the applied strain rate and thus causes an early fracture of the test sample. The fracture behavior of the Nd 60 Fe 20 Co 10 Al 10 bulk metallic glass is sensitive to strain rate. q

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Rate Dependence of Serrated Flow During Nanoindentation of a Bulk Metallic Glass

Cited by 163 publications

References 23 publications

Contact Deformation of Alumina

Contact Deformation of Alumina

Depth-sensing indentation tests in studying plastic instabilities

Strain rate-dependent compressive deformation behavior of Nd-based bulk metallic glass

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