Acoustic emission from plastic deformation of a pure single crystal

Chung, Jin Bok; Kannatey‐Asibu, Elijah

doi:10.1063/1.351652

Cited by 27 publications

(12 citation statements)

References 10 publications

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“…Combining nanoindentation and in situ imaging of tested areas [1][2][3][4] enables the evaluation of the initial stages of plastic deformation and fracture. [9][10][11] In most cases both energy-releasing and surface-interaction processes contribute to detected AE signals. Often, there is ambiguity even in highresolution post-test transmission electron microscopy (TEM) images of indented areas.…”

Section: Introductionmentioning

confidence: 99%

Highly localized acoustic emission monitoring of nanoscale indentation contacts

et al. 2003

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This study evaluated a novel approach for acoustic emission (AE) monitoring of nanoindentation. The technique utilizes a miniature AE sensor integrated into a calibrated diamond indenter tip on a commercial nanoindentation system. The evaluation focused on the yield-point phenomenon in W (100); MgO (100); and sapphire C (0001); R (1012); A (1210); and M (1010) single-crystal surfaces. The minimum amount of elastic energy release sufficient to produce AE signal detectable with the indenter tip sensor was nearly two orders of magnitude lower than the minimum energy level required for conventional AE sensors. Wave forms detected with the indenter tip sensor were independent of sample size. A linear relationship between released elastic energies and the corresponding AE energies was observed for all three evaluated materials. The scaling coefficient of the linear relationship was independent of indenter tip size/shape and indentation depth. The differences between the mechanisms of the initial stages of plasticity for the various crystallographic orientations of sapphire were reflected in the following aspects of AE activity: detection of a specific type of AE wave form that correlated to the presence of linear surface features near the indentation sites; AE signal associated with the yield point, consisting either of one or two distinct wave forms; and presence or absence of AE signals after the yield point. The possibility of plasticity onset in sapphire involving both slip and twinning is discussed.

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Section: Introductionmentioning

confidence: 99%

Highly localized acoustic emission monitoring of nanoscale indentation contacts

et al. 2003

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“…The scratch velocity controls the strain rate of deformation directly and many authors [16,17] have demonstrated that the AE is strongly dependent on strain rate, so the scratch velocity is expected to have a great impact on AE. Furthermore, temperature in the contact region caused by a high scratch velocity is somewhat analogous to strain rate and can influence a material's mechanical responses.…”

Section: Scratch Velocity and Aementioning

confidence: 99%

Acoustic emission in scratch processes of metals

Zhou¹,

He²,

Lu³

2015

Insight

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A series of scratch tests were carried out on two metals: molybdenum (Mo) and tungsten (W). The scratch process described herein is defined as a mechanical deformation process: the diamond indenter moves across the surface of the specimen and a groove is formed. Different types of scratch damage are observed in different materials. The relationship between acoustic emission (AE) signals and scratch damage is examined. The results show that the typical AE signals from the scratch process of Mo are composed of continuous waveforms and bursts with high amplitude, but only AE bursts are observed in the scratch process of W. It is concluded that the detected bursts are generated due to the cracks and the continuous waveforms are generated due to the ductile tearing. In addition, the AE amplitude, RMS, kurtosis and mean frequency change with increasing applied load and scratch velocity in different ways. The results of the AE mechanism are also discussed, considering the stress, strain rate and temperature.

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“…A change in _ can, in principle, be due to a change in m or a change in v [14]. Many experimental results [11,12,15] for AE during tensile testing showed that the mean square voltage (the AE power) of the continuous acoustic emission is proportional to the strain rate, which is expressed by…”

Section: Acoustic Emission During Plastic Deformationmentioning

confidence: 99%

Analysis of acoustic emission signals originating from bainite and martensite formation

Bohemen¹,

Sietsma²,

Hermans³

et al. 2005

Philosophical Magazine

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In this paper the characteristics of acoustic signals generated during bainite and martensite formation are studied. The results are discussed in a semiquantitative manner, since a thorough quantitative analysis of the signals is not feasible because of the limited frequency bandwidth of the system and the effect of internal sample reflections on the signal. The frequency spectra of acoustic emission signals are interpreted using a dislocation source model adopted from acoustic emission studies of plastic deformation. It is assumed that the predominant source of acoustic emission (AE) during displacive transformations is the movement of dislocations, i.e. the slip taking place during growth in order to relieve internal stresses. The results show that the mean frequency of AE signals generated during bainite formation is significantly larger than that of martensitic AE signals. This difference in the spectral density of the AE signals can be attributed to the difference in interface motion of the two transformations, and the consequent different behaviour of the dislocations involved.

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Acoustic emission from plastic deformation of a pure single crystal

Cited by 27 publications

References 10 publications

Highly localized acoustic emission monitoring of nanoscale indentation contacts

Highly localized acoustic emission monitoring of nanoscale indentation contacts

Acoustic emission in scratch processes of metals

Analysis of acoustic emission signals originating from bainite and martensite formation

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