An Evaluation of Superplasticity in Aluminum-Scandium Alloys Processed by Equal-Channel Angular Pressing

Berbon, Patrick B.; Komura, Shogo; Utsunomiya, Atsushi; Horita, Zenji; Furukawa, Mutsuhisa; Nemoto, Minoru; Langdon, Terence G.

doi:10.2320/matertrans1989.40.772

Cited by 77 publications

(41 citation statements)

References 25 publications

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“…9, a stress exponent of n ≈ 3.0 is calculated for all datum It is important to note that the testing conditions used in this investigation are significantly lower than the normal power-law breakdown which occurs at high stresses at a normalized strain rate of It is worth noting that, although the Al-3% Mg alloy in the present study failed to demonstrate true superplasticity at 673 K due to grain growth, Al-Mg alloys have a significant potential for achieving excellent superplastic ductilities especially when additions such as Sc and/or Zr are introduced to maintain an ultrafine-grained microstructure. For example, Al-3% Mg alloys with additions of Sc [55][56][57][58][59][60][61][62][63][64][65] and both Sc and Zr [64,66,67] demonstrated excellent superplastic elongations of up to >2000% at temperatures in the range of 573-723 K using strain rates of ~10 -4 -1.0 s -1 after processing though ECAP for 6-8 passes.…”

Section: High Temperature Mechanical Propertiesmentioning

confidence: 99%

Significance of grain refinement on microstructure and mechanical properties of an Al-3% Mg alloy processed by high-pressure torsion

Lee

Han

Janakiraman

et al. 2016

Journal of Alloys and Compounds

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Significance of grain refinement on microstructure and mechanical properties of an Al-3% Mg alloy processed by high-pressure torsion, Journal of Alloys and Compounds (2016), doi: 10.1016/ j.jallcom.2016 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 proof before it is published in its final 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.

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Section: High Temperature Mechanical Propertiesmentioning

confidence: 99%

Significance of grain refinement on microstructure and mechanical properties of an Al-3% Mg alloy processed by high-pressure torsion

Lee

Han

Janakiraman

et al. 2016

Journal of Alloys and Compounds

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“…5) These UFG materials have been produced by an expanding variety of processing techniques, such as mechanical alloying (MA), 6) crystallization of amorphous precursors 7) and severe plastic deformation (SPD). [8][9][10][11][12] Especially, there has been increasing interest in the SPD processes, such as equal channel angular pressing (ECAP), [8][9][10] high-pressure torsion (HPT) 11) and accumulative roll bonding (ARB). 12) In these processes, grain refinement occurs as a consequence of dynamical recovery and recrystallization through the rearrangement of dislocations which are generated in large quantities within materials by very large plastic strains.…”

Section: Introductionmentioning

confidence: 99%

Production of Ultra-Fine Grained Aluminum Alloy using Friction Stir Process

2003

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1050 aluminum alloy with an ultra-fine grain size was produced through friction stir process (FSP). The influence of tool rotation speed on the temperature profile, microstructure and mechanical properties of the friction stir processed zone (FZ) was also experimentally investigated. FSP was carried out with only a single pass at tool rotation speeds ranging from 560 to 1840 min À1 under a constant tool traverse speed of 155 mmÁmin À1 . The maximum temperature of the FZ was lower than the melting point of the workpiece material, although increasing linearly with the tool rotation speed. The cooling rate of the FZ also increased linearly from 341 to 1473 CÁmin À1 with the tool rotation speed. The FZ had very low dislocation density and was composed of fine equiaxed grains. These fine grains would result from the growth inhibition of dynamically recrystallized grains by the high cooling rate of the FZ. The grain size of the FZ increased with the tool rotation speed. However, it is noteworthy that, for 560 min À1 , the grain size decreased to even the submicron level in spite of only the single pass of FPS. The average hardness of the FZ increased significantly for 560 min À1 to about 37% as compared with the unprocessed zone (UZ), although decreasing with the increase in the tool rotation speed. For 560, 980 and 1350 min À1 , the tensile test specimens were fractured in the UZ. This result indicates that the tensile strength of the FZ increased more than that of the UZ by the grain refinement through FSP. Hence, it is concluded that FSP is very effective in producing an ultra-fine grained material with excellent mechanical properties. In addition, it is possible to control its grain size resulting in the mechanical properties by varying the maximum temperature with the tool rotation speed.

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“…The validity of this proposal has been demonstrated by several recent reports of high strain rate superplasticity above 10 À2 s À1 and low temperature superplasticity in aluminum and magnesium alloys processed by ECAE. [14][15][16][17] However, there have been few attempts to improve mechanical properties at room temperature, and to refine the microstructure of Zn-Al alloys by means of ECAE. [18][19][20] In existing investigations, the microstructure of such alloys has relatively large (0.6-1 mm) or elongated grains, due to an operating temperature of 373 K and initial grain size before ECAE of 1.0 mm or greater.…”

Section: Introductionmentioning

confidence: 99%

Superplasticity at Room Temperature in Zn-22Al Alloy Processed by Equal-Channel-Angular Extrusion

Tanaka

Higashi

2004

Mater. Trans.

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Equal-Channel-Angular extrusion (ECAE) has been conducted at room temperature in order to develop an ultrafine-grained structure in a Zn-22 mass% Al eutectoid alloy. The microstructures had an equiaxed and homogeneously distributed Al-rich and Zn-rich duplex-phase and its average grain size was about 0.35 mm. This alloy exhibited a large elongation of 240% albeit at room temperature and a high strain rate of 10 À2 s À1 . A grain-size-dependent phenomenon was also observed at lower strain rates. The activation energy was close to that for grain boundary diffusion. It was apparent that the deformation behavior at room temperature is consistent with that observed in conventional superplasticity. From the results, it was concluded that the dominant deformation mechanism was grain boundary sliding accommodated by dislocation movement controlled by grain boundary diffusion.

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An Evaluation of Superplasticity in Aluminum-Scandium Alloys Processed by Equal-Channel Angular Pressing

Cited by 77 publications

References 25 publications

Significance of grain refinement on microstructure and mechanical properties of an Al-3% Mg alloy processed by high-pressure torsion

Significance of grain refinement on microstructure and mechanical properties of an Al-3% Mg alloy processed by high-pressure torsion

Production of Ultra-Fine Grained Aluminum Alloy using Friction Stir Process

Superplasticity at Room Temperature in Zn-22Al Alloy Processed by Equal-Channel-Angular Extrusion

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