Capability of superplastic forming in the seismic device using Zn–22Al eutectoid alloy

Tanaka, Tsutomu; Makii, Koichi; Kushibe, Atsumichi; Kohzu, Masahide; Higashi, Kenji

doi:10.1016/s1359-6462(03)00328-2

Cited by 39 publications

(36 citation statements)

References 17 publications

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“…3, which also includes the results of earlier reports. 7,10,20,24,25) The grain size exponent, p-value, which is estimated from the slope of the line, was found to be 2 at lower strain rates. Several experimental results on superplasticity at high temperature in Zn-22Al alloys have also indicated p ¼ 2.…”

Section: Resultsmentioning

confidence: 98%

“…4,5) Such discoveries have enormous practical significance; for instance, it was reported recently that the ultrafine grained Zn-Al alloy could be applied as a seismic damper for high-rise buildings by attaining high strain rate superplasticity at room temperature. [6][7][8][9][10][11] Recently, severe plastic deformation (SePD) techniques such as equal-channel-angular extrusion (ECAE) or torsion straining (TS) have been seen as methods for producing bulk materials with ultrafine-grains. 12,13) The principle behind these techniques is to produce a very large strain in the sample; the rearrangement of the dislocations introduced by straining leads to a substantial grain refinement down to the submicrometer or even the nanometer scale.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 98%

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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“…8) The results are very attractive for commercial applications because the major problems in the current superplastic forming technique are very slow forming rates and high forming temperature. The investigations about press-forming are also carried out in order to put Zn-22 mass%Al alloy seismic damping device to practical use, [9][10][11][12][13] which reduce the vibration of buildings by absorbing the energy of an earthquake by undergoing plastic deformation before the main structure would undergo such deformation.…”

Section: Introductionmentioning

confidence: 99%

Cavitation Behavior in Superplastically Deformed Zn-22 mass%Al Alloy at Room Temperature

Tanaka

Higashi

2004

Mater. Trans.

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The cavitation behavior in room-temperature deformation was investigated for Zn-22 mass%Al alloy by metallographical observations, and compared with that in high-temperature deformation. It was predicted from metallographical observation that the critical cavity radius of transition in growth mechanism from diffusion-controlled to plasticity-controlled would exist. In the range of plasticity-controlled growth mechanism, the cavity growth parameter, , exhibited 1.65 and 2.45 in the deformation at high temperature and room temperature, respectively. In primary period of straining, cavities in room-temperature deformation could be nucleated more easily compared with those in hightemperature deformation. The experimental cavity growth rates in both conditions were almost same at cavity size of about 1 mm.

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“…All these requirements should be fulfilled so that the grain boundary sliding (GBS) can occur easily as the main deformation mechanism in superplastic region [3]. After the first report in 1912 [4], superplasticity-related studies have been one of the main topics among the material scientists and mechanical engineers, and various classes of materials including alloys [5][6][7][8][9][10][11][12][13][14][15][16][17][18], ceramics [19][20][21] and amorphous materials [22,23] have been addressed for this purpose.…”

Section: Introductionmentioning

confidence: 99%

“…However, it should be noted that it is not possible to achieve RT superplasticity in all UFG or NS materials. RT and HSR superplastic behavior can be achieved in some specific alloys like Sn-Bi [24], Pb-Tl [25], Pb-Sn [26], and Zn-Al [5][6][7][8][9][10][11][12][13][14][15][16][17][18] due to their relatively low melting points. Among them, Zn-Al alloy family is the most suitable one as considering its phase diagram shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Effect of chemical composition and grain size on RT superplasticity of Zn-Al alloys processed by ECAP

Demirtas¹,

Pürçek²,

Yanar³

et al. 2015

LoM

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Dilute Zn-0.3Al, eutectic Zn-5Al and eutectoid Zn-22Al alloys were processed by multi-pass equal channel angular pressing (ECAP) in order to achieve fine grained (FG) or ultrafine-grained (UFG) microstructure and room temperature (RT) superplasticity. ECAP refined the microstructure of Zn-0.3Al and resulted in a FG Zn-rich η-matrix with an average grain size of 2 µm and homogeneously distributed nano-sized Al-rich α-particles with the grain sizes in the range of 50-200 nm. A bi-modal microstructure was achieved in Zn-5Al alloy with UFG Al-rich α-and FG Zn-rich η-phases having mean grain sizes of 110 nm and 540 nm, respectively. ECAP brought about an agglomerate-free UFG microstructure in Zn-22Al alloy with an average grain size of 200 nm which is the lowest one obtained so far for this alloy after ECAP processing. The maximum RT superplastic elongations of 1000%, 520% and 400% were achieved for Zn-0.3Al, Zn-5Al and Zn-22Al alloys, respectively. Considering the RT superplasticity in Zn-Al alloys, it was found that lower Al content results in higher superplastic elongations even if the alloy has relatively larger grain size. Grain boundary sliding (GBS) was found to be the main deformation mechanism in region-II as the optimum superplastic region during RT deformation for all three Zn-Al alloys with the strain rate sensitivity factor ranging between 0.25-0.31.Keywords: Zn-Al alloys, room temperature superplasticity, ultrafine-grained materials, equal channel angular pressing Влияние химического состава и размера зерен на сверхпластичность при комнатной температуре сплавов Zn-Al, подвергнутых РКУП Низколегированный сплав Zn-0.3Al, эвтектик Zn-5Al и эвтектоидный сплав Zn-22Al были подвергнуты многопро-ходному равноканальному угловому прессованию (РКУП) с целью получения мелкозернистой (МЗ) или ультрамел-козернистой (УМЗ) структуры и достижения сверхпластичности при комнатной температуре. РКУП привело к из-мельчению микроструктуры Zn-0.3Al и формированию МЗ обогащенной Zn η-матрицы со средним размером зерен 2 мкм и однородно распределенных наноразмерных богатых Al α-частиц с размером в интервале 50-200 нм. В сплаве Zn-5Al была получена бимодальная структура с УМЗ богатой Al α-фазой и МЗ богатой Zn η-фазой, имеющими соответственно размеры зерен 110 нм и 540 нм. В сплаве Zn-22Al РКУП привело к формированию не агломериро-ванной УМЗ микроструктуры со средним размером зерен 200 нм, что представляет собой минимальное достигнутое к настоящему времени значение размера зерен, полученное РКУП на данном сплаве. Для сплавов Zn-0.3Al, Zn-5Al и Zn-22Al были получены максимальные сверхпластические удлинения при комнатной температуре, равные соот-ветственно 1000%, 520% и 400%. По отношению к сверхпластичности сплавов Zn-Al показано, что более низкое содержание Al приводит к более высоким сверхпластическим удлинениям, даже если сплав имеет больший размер зерен. Показано, что зернограничное проскальзывание (ЗГП) является основным механизмом деформации в обла-сти II, являющейся оптимальной областью сверхпластической деформации при комн...

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Capability of superplastic forming in the seismic device using Zn–22Al eutectoid alloy

Cited by 39 publications

References 17 publications

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

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

Cavitation Behavior in Superplastically Deformed Zn-22 mass%Al Alloy at Room Temperature

Effect of chemical composition and grain size on RT superplasticity of Zn-Al alloys processed by ECAP

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