On the origin of the extremely high strength of ultrafine-grained Al alloys produced by severe plastic deformation

Valiev, Ruslan Z.; Enikeev, Nariman A.; Murashkin, M. Yu.; Kazykhanov, Vil U.; Sauvage, Xavier

doi:10.1016/j.scriptamat.2010.07.014

Cited by 287 publications

(164 citation statements)

References 15 publications

(16 reference statements)

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“…In order to verify whether the grain boundary strengthening predicted by the Hall-Petch relationship remains consistent for the UFG Al-3Mg-0.2Sc alloy, Fig. 9 plots the yield stress,  y , against the inverse square root of the grain size using both the experimental data obtained in this investigation and data from other studies conducted on commercially pure aluminium [86][87][88][89], Al-Mg alloys [10,18,20,51,[90][91][92] and Al-Mg-Sc alloys [37,[42][43][44]93].…”

Section: Examining the Validity Of The Hall-petch Relationship In Al-mentioning

confidence: 92%

“…The absence of a breakdown in the Hall-Petch relationship suggests that the deformation is primarily controlled by intragranular dislocation motion and the contribution from the emission and annihilation of extrinsic dislocations at the non-equilibrium grain boundaries may be diminished by the presence of Mg segregation at HAGBs and triple junctions [42]. Thus, high concentrations of Mg solutes were detected at grain boundaries in SPD-processed Al-Mg alloys [95][96][97][98].…”

Section: Examining the Validity Of The Hall-petch Relationship In Al-mentioning

confidence: 96%

“…Although the superplastic properties of Al-Mg-Sc alloys were studied extensively after ECAP [24,25,28,[32][33][34][35][36][37] and HPT [38][39][40][41], there are only limited studies documenting the mechanical properties of UFG Al-Mg-Sc alloys at ambient temperatures [42][43][44][45].…”

Section: Introductionmentioning

confidence: 99%

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Influence of grain size on the flow properties of an Al-Mg-Sc alloy over seven orders of magnitude of strain rate

Pereira

Wang

Huang

et al. 2017

Materials Science and Engineering: A

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractExperiments were conducted to evaluate the flow properties of an Al-3Mg-0.2Sc alloy both without and with processing using equal-channel angular pressing (ECAP). The initial grain size was ~300 m and this was reduced to ~250 nm by ECAP and then increased to ~600 nm by annealing at 673 K for 10 min. Tests were conducted to determine the mechanical properties over seven orders of magnitude of strain rate from ~10 -4 to ~10 3 s -1 .The results confirm the validity of the Hall-Petch relationship in the material processed by ECAP. Shear banding occurred in the coarse-grained material during dynamic testing but in the ECAP-processed alloy there was only minor grain coarsening. There was evidence for dynamic strain ageing in both the coarse and the ultrafine-grained (UFG) alloy with a transition in flow mechanism at high temperatures from dislocation climb in the coarsegrained material to superplasticity in the UFG alloy.

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Section: Examining the Validity Of The Hall-petch Relationship In Al-mentioning

confidence: 92%

Section: Examining the Validity Of The Hall-petch Relationship In Al-mentioning

confidence: 96%

See 1 more Smart Citation

Influence of grain size on the flow properties of an Al-Mg-Sc alloy over seven orders of magnitude of strain rate

Pereira

Wang

Huang

et al. 2017

Materials Science and Engineering: A

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“…[146,147] Some experimental evidence is now available for the positive slope at very small grain sizes [148] and generally the strengthening is attributed to the presence of significant grain boundary segregation at grain sizes smaller than ~100 nm. [149,150] This is an area requiring further investigation but generally it is reasonable to anticipate SPD materials will exhibit improved strength and improved functional properties associated not only with their ultrafine grains but also with other nanostructural features that are not generally available in conventional coarse-grained materials. [151] VI.…”

Section: Superstrength By Spdmentioning

confidence: 99%

The Strength–Grain Size Relationship in Ultrafine-Grained Metals

Balasubramanian

Langdon

2016

Metall Mater Trans A

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Metals processed by severe plastic deformation [SPD] techniques, such as equal-channel angular pressing [ECAP] and high-pressure torsion [HPT], generally have submicrometer grain sizes. Consequently, they exhibit high strength as expected on the basis of the HallPetch [H-P] relationship. Examples of this behavior are discussed using data on Ti, Al-Mg 1 and Ni. These materials typically have grain size above ~50 nm where softening is not expected. An increase in strength is usually accompanied by a decrease in ductility. High strength and ductility can be achieved simultaneously by imposing high strains to give both ultrafine grain sizes and a high fraction of high-angle grain boundaries. An example is presented for a cast Al-7% Si alloy processed by HPT. In some cases, SPD may produce a fine grain size but also lead to a weakening due to microstructural changes as in ECAP of an Al-7034 alloy and HPT of Zn-22% Al. In SPD-processed materials, grain boundary segregation and nanostructural features are present which may lead to higher strengths than those predicted by the H-P relationship in some alloys having nano grain sizes.

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“…More specifically, several earlier reports investigated the capability of HPT processing of solid solution Al-Mg-Si alloys to stimulate solute segregation to grain boundaries (GBs) [10,[19][20][21][22]. However, a comparatively smaller number of works have dealt with age-hardened Al-Mg-Si alloys.…”

Section: Introductionmentioning

confidence: 99%

Controlling the high temperature mechanical behavior of Al alloys by precipitation and severe straining

Cepeda-Jiménez

Castillo-Rodríguez

Molina-Aldareguia

et al. 2017

Materials Science and Engineering: A

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The aim of this work was to investigate the influence of the precipitate distribution on the microstructure and on the room and high temperature mechanical properties of an age-hardenable aluminium AA6082 alloy following severe straining by high-pressure torsion (HPT). With this goal, specimens in the as-cast and T6 peak-aged conditions were processed by HPT using 0.5, 1 and 5 turns at room temperature. At high strain levels (J>100), similar saturation grain sizes (~250 nm), high-angle boundary fractions (~80%) and hardness values (Hv~160) were obtained for both initial conditions. Grain refinement led to significant strengthening and to good ductility values at room temperature. Analysis by TEM and EDS elemental mapping revealed that HPT processing of the as-cast condition led to fracture of the stable E-phase into many small precipitates located preferentially along grain boundaries and triple junctions. By contrast, HPT processing of the T6 peak-aged specimens revealed a partial dissolution of the needle-shaped nanoprecipitates. The different evolutions of the precipitate distributions following straining in the as-cast and peak-aged conditions gave rise to dramatic differences in the mechanical properties and the operative deformation mechanisms at warm temperatures. These results provide evidence that the high temperature mechanical behavior of age-hardenable Al alloys may be conveniently controlled by altering the precipitate distribution followed by severe straining.

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On the origin of the extremely high strength of ultrafine-grained Al alloys produced by severe plastic deformation

Cited by 287 publications

References 15 publications

Influence of grain size on the flow properties of an Al-Mg-Sc alloy over seven orders of magnitude of strain rate

Influence of grain size on the flow properties of an Al-Mg-Sc alloy over seven orders of magnitude of strain rate

The Strength–Grain Size Relationship in Ultrafine-Grained Metals

Controlling the high temperature mechanical behavior of Al alloys by precipitation and severe straining

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