Acoustic emission monitoring of the earliest stages of contact-induced plasticity in sapphire

Tymiak, N. I.; Daugela, Antanas; Wyrobek, Thomas J.; Warren, Oden L.

doi:10.1016/j.actamat.2003.09.039

Cited by 65 publications

(72 citation statements)

References 35 publications

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“…5). According to the arguments developed in [18], type 2 pattern may be associated with a twinning process. The first high-frequency burst should correspond to the initial high-rate energy release occurring during twin initiation.…”

Section: Twinning and Dislocation Glidementioning

confidence: 99%

“…Accordingly, in case of a twinning event, A 0 might still be related to the deformation achieved by the avalanche, but then the corresponding coefficient of proportionality should be much higher than in the case of a slip event. In fact, some studies [14,18] tried to compare final twin extents (from post-mortem microstructural analyses) to the characteristics of associated AE signals, but found no straightforward correlation. Hence, in case of twinning, the relation between deformation and AE is not clear and remains an open question.…”

Section: Ae Activitymentioning

confidence: 99%

“…Therefore, the type 1 pattern could be indicative of a dislocation glide avalanche, as those observed in ice [8]. In [18], the distinction between the two types of patterns was evaluated in terms of the ratio between AE maximum amplitude (A 0 ) and AE root mean square amplitude (A rms ). This parameter characterizes the distribution of signal energy over its time span.…”

Section: Twinning and Dislocation Glidementioning

confidence: 99%

See 2 more Smart Citations

On the critical character of plasticity in metallic single crystals

Richeton

Dobroň

Chmelı́k

et al. 2006

Materials Science and Engineering: A

118

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Abstract:Previous acoustic emission (AE) experiments on ice single crystals, as well as numerical simulations, called for the possible occurrence of self-organized criticality (SOC) in collective dislocation dynamics during plastic deformation. Here, we report AE experiments on hcp metallic single crystals. Dislocation avalanches in relation with slip and twinning a re identified with the only sources of AE. Both types of processes exhibit a strong intermittent character. The AE waveforms of slip and twinning events seem to be different, but from the point of view of the AE event energy distributions, no distinction i s possible. The distributions always follow a power law given by P(E)~E -τ E , with τ Ε = 1.5±0.1, even when multi-slip and forest hardening occur. The exponent τ Ε is in perfect agreement with those previously found in ice single crystals. Along with observed time clustering and interactions between avalanches, these results are new and strong arguments in favour of a general, SOCtype, framework for crystalline plasticity.

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Section: Twinning and Dislocation Glidementioning

confidence: 99%

Section: Ae Activitymentioning

confidence: 99%

Section: Twinning and Dislocation Glidementioning

confidence: 99%

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On the critical character of plasticity in metallic single crystals

Richeton

Dobroň

Chmelı́k

et al. 2006

Materials Science and Engineering: A

118

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“…Blunt indenters (generally spherical or conical) produce an elastic deformation of the material. The high levels of hydrostatic compression generated during normal indentation and sliding contacts facilitate activation of different plastic deformation mechanisms such as dislocations, twining, and kink bands [7]. Contactinduced deformation mechanisms are highly dependent on the crystallographic orientation of the surface evaluated.…”

Section: Introductionmentioning

confidence: 99%

Nanoindentation of Bridgman YBCO samples

Roa

Konstantopoulou

Jiménez‐Piqué

et al. 2012

Ceramics International

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In this study, the mechanical properties of YBa2Cu30 7 _ x , obtained by the Bridgman technique, were examined using a Berkovich tip indenter on the basal plane (0 0 1). Intrinsic hardness was measured by nanoindentation tests and corrected using the Nix and Gao model for this material. Furthermore, Vickers hardness tests were performed, in order to determine the possible size effect on these measurements. The results showed an underestimation of the hardness value when the tests were performed with large loads. Moreover, the elastic modulus of the Bridgman samples was 128 ± 5 GPa. Different residual imprints were visualised by atomic force microscopy and a focused ion beam, in order to observe superficial and internal fracturing. Mechanical properties presented a considerable reduction at the interface. This effect could be attributed to internal stress generated during the texturing process. In order to corroborate this hypothesis, an observation using transmission electron microscopy was performed.

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“…Figure 1 shows loss tangent (ratio of loss modulus to storage modulus) in an image format for a phasesegregated polymer blend. For certain classes of materials (e.g., ceramics and metals), a more appropriate mixed-mode technique is in-situ acoustic emission monitoring of nanoindentation [4] for detecting high-speed deformation transients associated with the onset of plasticity, phase transformation, fracture, or delamination. The manner of controlling the indentation process also has evolved.…”

mentioning

confidence: 99%

Recent Advancements in Nanomechanical Characterization Techniques and Associated Technologies

Warren

Asif

Dwivedi

et al. 2005

MAM

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Nanoindentation [1] is a widely used technique for quantifying mechanical properties of microscale to nanoscale volumes of materials of relevance to shrinking technologies such as microelectronics, hard disk drives, and microelectromechanical systems. A particularly successful class of nanoindentation instrumentation is the scanning nanoindenter, which is capable of conducting scanning probe microscopy using the indentation probe as the imaging stylus. Although extracting elastic modulus and hardness from nanoindentation tests does not require direct observation of the residual indentation impression for the purpose of measuring its size, the ability to visualize surfaces in the sub-optical regime has proven to be empowering nonetheless. Intimate knowledge of the position of the indentation probe in relationship to specific surface features enables site-specific mechanical characterization of engineered microstructures, individual grains and phases of materials, and nanoparticles, as examples. Moreover, re-examination of the surface after completing the nanoindentation test can provide valuable insight into the deformation mechanism at hand.In recent years, nanoindentation technology has evolved from relatively simple instruments dedicated solely to quasistatic operation (slow loading and unloading) to nanomechanical / nanotribological test platforms supporting nanoscratch and nanowear (or nanomachining) experimentation, plus a host of novel mixed-mode techniques. Techniques involving dynamic forces superimposed onto quasistatic forces include the nanoscale analogue of dynamic mechanical (thermal) analysis [2] for determining complex modulus (storage and loss components) as a function of depth, frequency, or temperature, and a method of complex modulus imaging [3] for differentiating material phases on the basis of their spatial distribution of complex modulus. Figure 1 shows loss tangent (ratio of loss modulus to storage modulus) in an image format for a phasesegregated polymer blend. For certain classes of materials (e.g., ceramics and metals), a more appropriate mixed-mode technique is in-situ acoustic emission monitoring of nanoindentation [4] for detecting high-speed deformation transients associated with the onset of plasticity, phase transformation, fracture, or delamination. The manner of controlling the indentation process also has evolved. Recent work in augmenting the familiar PID control algorithm with a predictive feedforward loop [5] has considerably improved the performance of both load-controlled and depthcontrolled operation.For any important technique, the process of growing from infancy to maturity eventually leads to a major paradigm shift in usage. In the early years, nanomechanical testing typically involved a single sample mounted on the instrument and perhaps ten nanoindentation tests per sample. Today, nanoindenters are being exploited as screening tools in a number of combinatorial materials science workflows. Such high-throughput research environments demand reconsideration of the defi...

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Acoustic emission monitoring of the earliest stages of contact-induced plasticity in sapphire

Cited by 65 publications

References 35 publications

On the critical character of plasticity in metallic single crystals

On the critical character of plasticity in metallic single crystals

Nanoindentation of Bridgman YBCO samples

Recent Advancements in Nanomechanical Characterization Techniques and Associated Technologies

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