Dislocation creep behavior in Mg–Al–Zn alloys

Somekawa, Hidetoshi; Hirai, Kinji; Watanabe, Hiroyuki; Takigawa, Yorinobu; Higashi, Kenji

doi:10.1016/j.msea.2005.06.059

Cited by 271 publications

(121 citation statements)

References 49 publications

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“…This consistency in the AZ91 alloy has not been observed in the AZ31 alloy or AZ91 alloy processed by ECAP [26] and FSP [27]. This is attributed to the difference in the aluminium content and stacking fault energy in both alloys, which control the extent of grain refinement, dislocation density, achieved homogeneity and resultant mechanical properties [14,21,38]. The behaviour of strain hardening and homogeneity of microhardness in the AZ91 alloy follows a standard model of hardness evolution with increasing equivalent strain reported in earlier work [20].…”

Section: Development Of Microhardnessmentioning

confidence: 89%

“…The high value of applied pressure has also been reported to enhance the obstruction of defect migration in the processed material and then promotes the suppression of dislocation annihilation [45,46]. The low stacking fault energy in the AZ91 alloy leads to a significant inhibition of dislocation cross-slip, and formation of a high density of planar arrays of dislocations has also been reported [10,38].…”

Section: Development Of Microhardnessmentioning

confidence: 96%

“…The AZ91 alloy processed in HPT showed an earlier saturation in the microhardness distribution than for the AZ31 alloy [21] processed in HPT at room temperature. The stacking fault energy is lower, and the fraction of particles of b-phase is higher in the AZ91 alloy than for the AZ31 alloy [38,39]. Therefore, the evolution of grain refinement and strain hardening occurred at faster rates in the AZ91 alloy than for the AZ31 alloy.…”

Section: Development Of Microhardnessmentioning

confidence: 96%

“…The development of microhardness after HPT processing depends on the stacking fault energy of the alloy [10,19]. The AZ91 alloy with a low stacking fault energy [38] shows a slow rate of dynamic recovery during processing at room temperature, thus strain hardening occurs at a fast rate during processing [20,32]. The AZ91 alloy processed in HPT showed an earlier saturation in the microhardness distribution than for the AZ31 alloy [21] processed in HPT at room temperature.…”

Section: Development Of Microhardnessmentioning

confidence: 99%

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Evolution of microstructure in AZ91 alloy processed by high-pressure torsion

et al. 2015

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An investigation has been conducted on AZ91 magnesium alloy processed in high-pressure torsion (HPT) at 296, 423 and 473 K for different numbers of turns. The microstructure has altered significantly after processing at all processing temperatures. Extensive grain refinement has been observed in the alloy processed at 296 K with apparent grain sizes reduced down to 35 nm. Segmentation of coarse grains by twinning has been observed in the alloy processed at 423 K and 473 K with average apparent grain sizes of 180 nm and 250 nm. Substantial homogeneity in microhardness has been observed in the alloy processed at 296 K compared to that found at 423 K and 473 K. The ultrafine-grained AZ91 alloy exhibited a significant dependence of the yield strength on grain size as shown by the microhardness measurements, and it obeys the expected Hall-Petch relationship. The alloying elements, fraction of nano-sized particles of b-phase, and the dominance of basal slip and pyramidal modes have additional effects on the strengthening of the alloy processed at 296 K.

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Section: Development Of Microhardnessmentioning

confidence: 89%

Section: Development Of Microhardnessmentioning

confidence: 96%

Section: Development Of Microhardnessmentioning

confidence: 96%

Section: Development Of Microhardnessmentioning

confidence: 99%

See 2 more Smart Citations

Evolution of microstructure in AZ91 alloy processed by high-pressure torsion

et al. 2015

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“…aluminum. [11][12][13][14] This suggests that grain refinement by dynamic recrystallization (DRX) readily occurs in magnesium, and thus, hot deformation accompanied by DRX should be a promising method for refining microstructures. To date, the grain refinement due to DRX during hot deformation has been demonstrated in conventional Mg-Al-Zn alloys.…”

Section: Introductionmentioning

confidence: 99%

Effect of Initial Grain Size on Dynamically Recrystallized Grain Size in AZ31 Magnesium Alloy

et al. 2008

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The effect of initial grain size on dynamically recrystallized grain size (DRX grain size) is examined in AZ31 magnesium alloy with four kinds of initial grain sizes. When the average grain size after the high-temperature compression test is plotted against Zenner-Hollomon parameter (Z-parameter), initial grain size dependence on DRX grain size appears only in the specimen with large initial grain size in the low Z region, but not in the specimen with small grain size or in high Z region. When the grain size measured only in recrystallized region is plotted against Z-parameter, initial grain size dependence on DRX grain size does not appear. From these results, it is concluded that there is no initial grain size dependence on DRX grain size when the DRX proceeds to some degree, because the DRX grain size becomes constant for a given Zvalue. The initial grain size dependence on DRX grain size observed in the low Z region would be related to the rotation of basal plane perpendicular to the compression axis during deformation before the DRX grains have been developed sufficiently.

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Theoretical derivation of flow laws for quartz dislocation creep: Comparisons with experimental creep data and extrapolation to natural conditions using water fugacity corrections

Fukuda

Shimizu

2017

JGR Solid Earth

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We theoretically derived flow laws for quartz dislocation creep using climb‐controlled dislocation creep models and compared them with available laboratory data for quartz plastic deformation. We assumed volume diffusion of oxygen‐bearing species along different crystallographic axes (//c, ⊥R, and ⊥c) of α‐quartz and β‐quartz, and pipe diffusion of H2O, to be the elementary processes of dislocation climb. The relationships between differential stress (σ) and strain rate ( trueε˙) are written as trueε˙∝σ3Dv and trueε˙∝σ5Dp for cases controlled by volume and pipe diffusion, respectively, where Dv and Dp are coefficients of diffusion for volume and pipe diffusion. In previous experimental work, there were up to ~1.5 orders of magnitude difference in the water fugacity values in experiments that used either gas‐pressure‐medium or solid‐pressure‐medium deformation apparatus. Therefore, in both the theories and flow laws, we included water fugacity effects as modified preexponential factors and water fugacity terms. Previous experimental data were obtained mainly in the β‐quartz field and are highly consistent with the volume‐diffusion‐controlled dislocation creep models of β‐quartz involving the water fugacity term. The theory also predicts significant effects for the transition of α‐β quartz under crustal conditions. Under experimental pressure and temperature conditions, the flow stress of pipe‐diffusion‐controlled dislocation creep is higher than that for volume‐diffusion‐controlled creep. Extrapolation of the flow laws to natural conditions indicates that the contributions of pipe diffusion may dominate over volume diffusion under low‐temperature conditions of the middle crust around the brittle‐plastic transition zone.

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Dislocation creep behavior in Mg–Al–Zn alloys

Cited by 271 publications

References 49 publications

Evolution of microstructure in AZ91 alloy processed by high-pressure torsion

Evolution of microstructure in AZ91 alloy processed by high-pressure torsion

Effect of Initial Grain Size on Dynamically Recrystallized Grain Size in AZ31 Magnesium Alloy

Theoretical derivation of flow laws for quartz dislocation creep: Comparisons with experimental creep data and extrapolation to natural conditions using water fugacity corrections

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