On the influence of the grain size and solute content on the AE response of magnesium alloys tested in tension and compression

Bohlen, Jan; Dobroň, Patrik; Swiostek, J.; Letzig, Dietmar; Chmelı́k, František; Lukáč, P.; Kainer, Karl Ulrich

doi:10.1016/j.msea.2006.02.470

Cited by 159 publications

(78 citation statements)

References 23 publications

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“…However, there is significant stress-strain data on textured polycrystals with either controlled solute concentrations or commercial compositions, and these studies have been used to estimate the stresses needed to drive twinning. Ref [89] contains an analysis of earlier experimental data for AZ31 [90,91,92,93], AZ61 and AZ80 [91] at various grain sizes. The twinning yield stress for these alloys can be determined from the results at a (large) grain size of 100 µm and applying the appropriate Schmid factor (m = 0.37) [89].…”

Section: Twinning In Mgmentioning

confidence: 99%

Solute strengthening in random alloys

et al. 2017

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Random solid solution alloys are a broad class of materials that are used across the entire spectrum of engineering metals, whether as stand-alone materials (e.g. Al-5xxx alloys) or as the matrix in precipitatestrengthening materials (e.g. Ni-based superalloys). As a result, the mechanisms of, and prediction of, strengthening in solid solutions has a long history. Many concepts have been developed and important trends identified but predictive capability has remained elusive. In recent years, a new theory has been developed that builds on one historical model, the Labusch model, in important ways that lead to a well-defined model valid for random solutions with arbitrary numbers of components and compositions. The new theory uses first-principles-computed solute/dislocation interaction energies as input, from which specific predictions emerge for the yield strength and activation volume as a function of alloy composition, temperature, and strain-rate. Being a general model for materials that otherwise have a low Peierls stress, it has broad application and has been successfully applied to Al-X alloys, Mg-Al, twinning in Mg alloys, and recently fcc High-Entropy Alloys. Here, the new theory is presented in a general and systematic manner. Approximations and limiting cases that reduce the complexity and facilitate understanding are introduced, and help relate the new model to various physical features present among the historical array of models. The quantitative predictions of the model in the various materials above is then demonstrated.

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Section: Twinning In Mgmentioning

confidence: 99%

Solute strengthening in random alloys

et al. 2017

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“…On the other hand, twinning is not preferentially activated if the stress is initially applied in tensile testing as e.g. shown by [1,4,7]. However, during the tensile test segment of samples which were subjected to compressive pre-straining, the stressstrain curves show the typical compression test form.…”

Section: Methodsmentioning

confidence: 99%

“…Firstly, the yield asymmetry decreases with decreasing average grain size [7]. This is understood to result from an increase of the twinning stress with decreasing grain size, which leads to a more distinct increase of the yield stress if the plastic ow is twin dominated [1,8].…”

Section: Introductionmentioning

confidence: 99%

“…dierent amplitude levels for counting are applied [11]. A continuous AE with lower amplitude is typically the result of dislocation glide whereas burst type emission with higher amplitudes is the result of massive dislocation glide, twinning or local cracking [7,12]. In this paper, the inuence of compressive pre--straining on a subsequent tensile test segment is examined, in order to reveal the grain size dependences and (444) twinning activities during testing.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Reversed Loading Conditions on the Mechanical Behaviour of Extruded Magnesium Alloy AZ31

et al. 2012

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An indirectly extruded round bar of magnesium alloy AZ31 has been subjected to a cyclic test consisting of preloading in compression to dierent values of maximum stress followed by a single tensile test segment. Concurrent acoustic emission measurements were used to determine the active deformation mechanisms during plastic ow and work hardening. Electron backscattering diraction was applied to obtain local orientation images in order to reveal twins and twinned fractions of the microstructure. Twins form preferentially in larger grains during the compression test segment and only with increasing stress do smaller grains show twinning. Some grains are completely re-oriented as a result of twinning. During the tensile test segment, untwinning is the most signicant deformation mechanism although in some re-oriented grains new twins also nucleate. The acoustic emission count rates conrm that this is only the case after compression to higher stress levels.

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“…Thus, deformation twinning is favored if a compressive stress is applied along the extrusion direction [4]. Therefore, Mg alloys show anisotropic and asymmetric properties at the yield point in tension and compression [5].…”

Section: Introductionmentioning

confidence: 99%

On the Effect of the Extrusion Speed on Microstructure and Plastic Deformation of ZE10 and ZEK100 Magnesium Alloys - an Acoustic Emission Study

et al. 2012

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MgZn-based alloys ZE10 and ZEK100 have been extruded at dierent speeds varying from 1 m/min to 20 m/min. Specimens taken in the extrusion direction were uniaxially loaded in tension and compression at room temperature. The results are discussed using concurrent acoustic emission monitoring during mechanical testing and the acoustic emission signal analysis that correlates the microstructure and the stressstrain curves to the possible deformation mechanisms. In all tests, the acoustic emission response exhibited a large acoustic emission peak at the beginning of plastic deformation. A small local maximum on the onset of the acoustic emission activity was frequently observed, i.e. at very low stresses. For the alloys with bimodal grain structure tested in compression, an additional acoustic emission peak appeared at larger strains. This peculiar behavior can be explained by interplay of (1012)-twinning and dislocation slip in samples with various grain size distributions.

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On the influence of the grain size and solute content on the AE response of magnesium alloys tested in tension and compression

Cited by 159 publications

References 23 publications

Solute strengthening in random alloys

Solute strengthening in random alloys

The Effect of Reversed Loading Conditions on the Mechanical Behaviour of Extruded Magnesium Alloy AZ31

On the Effect of the Extrusion Speed on Microstructure and Plastic Deformation of ZE10 and ZEK100 Magnesium Alloys - an Acoustic Emission Study

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