Microtexture analysis of restoration mechanisms during high pressure torsion of pure nickel

Ghosh, Pradipta; Renk, Oliver; Pippan, Reinhard

doi:10.1016/j.msea.2016.12.032

Cited by 48 publications

(34 citation statements)

References 44 publications

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“…In addition, the material processed by ECAP at 600 K depicts significantly larger grain sizes than the Al alloy processed at 300 K. These results are consistent with earlier studies with Al-Mg-Sc alloys [7][8][9][17][18][19][20][21][22][23] and are associated with the higher strain rates in the UFG metal during HPT processing as well as with the increasing action of dynamic softening mechanisms during deformation at higher homologous temperatures, T/T m , as reported for various fcc metals [25,33]. It is also clearly demonstrated in Fig.…”

Section: Discussionsupporting

confidence: 90%

“…The Al3Mg-0.2Sc alloy processed through 10 turns of HPT exhibits exceptional superplastic elongations at low homologous temperatures [19,20,24], although there are only few and isolated studies evaluating the microstructural changes in this metal when exposed to high temperatures [18,22,24]. Furthermore, it was revealed in recent studies that the microstructural stability in pure Ni [25] and the superplastic properties in Mg alloys [26,27] are significantly enhanced by conducting HPT processing at high temperatures and, to date, there have been no studies dedicated to assess the superplastic properties of Al-Mg-Sc alloys processed by HPT at an elevated temperature.…”

Section: Introductionmentioning

confidence: 99%

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Thermal stability and superplastic behaviour of an Al-Mg-Sc alloy processed by ECAP and HPT at different temperatures

Pereira

Huang

Langdon

2017

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. An Al-3%Mg-0.2%Sc alloy was processed by ECAP and HPT at different temperatures. Afterwards, samples subjected to 10 turns of HPT at 300 and 450 K, 8 passes of ECAP at 300 K and 10 passes of ECAP at 600 K were annealed for 1 hour at 523 K and their mechanical properties and microstructure were examined using microhardness measurements and EBSD analysis. In addition, tensile specimens with similar dimensions were machined from the HPT and ECAP-processed materials and further tensile tested at 523 K. The results demonstrate that the Al alloy processed by HPT at 450 K exhibits higher microhardness values (~138 Hv) and a smaller average grain size (~0.28 µm) after annealing at 523 K among all SPD processing conditions. Accordingly, the material subjected to HPT at an elevated temperature displays superior superplastic properties such that an elongation of ~1020 % was attained after testing at 523 K at 1.0 × 10 -3 s -1 . Furthermore, detailed EBSD analysis revealed a significant fraction of low-angle grain boundaries (LAGBs > 33 %) in the ECAP-processed material after annealing which may be responsible for the inferior superplastic behaviour by comparison with the HPT-processed samples (LAGBs < 13 %) tested at 523 K.

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Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Thermal stability and superplastic behaviour of an Al-Mg-Sc alloy processed by ECAP and HPT at different temperatures

Pereira

Huang

Langdon

2017

IOP Conf. Ser.: Mater. Sci. Eng.

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“…In the current study, discontinuous grain growth is clearly evident in the HPT-processed Al-3Mg-0.2Sc alloy after annealing for 1 h at 623 and 673 K. Accordingly, as these temperatures are equivalent to the transition temperature between continuous and discontinuous precipitation of Al 3 Sc dispersoids in Al-Sc alloys, it is readily apparent that the formation of a bi-modal grain structure in the Al-3Mg-0.2Sc alloy is directly associated with the occurrence of discontinuous precipitation in the HPT-processed material during annealing. Furthermore, the continuous precipitation of Al 3 Sc dispersoids at T ≤ 573 K inhibits the occurrence of abnormal grain growth at low homologous temperatures as observed for pure nickel after processing by 10 turns of HPT at 300 K and further annealing at 448 K 34 . The formation of a duplex structure in UFG materials after annealing was also reported for an Al-3Mg alloy processed by ECAP 14 and ECAP + cold rolling 13 .…”

Section: Discussionmentioning

confidence: 98%

Examining the Thermal Stability of an Al-Mg-Sc Alloy Processed by High-Pressure Torsion

2017

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An Al-3%Mg-0.2%Sc alloy was solution treated and subjected to 10 turns of high-pressure torsion (HPT). Thereafter, the HPT-processed material was annealed for 1 hour at temperatures ranging from 423 to 773 K and its mechanical properties and microstructural evolution were examined using microhardness measurements and EBSD analysis. The results demonstrate that the Al-Mg-Sc alloy exhibits an average microhardness of ~190 Hv and an average grain size of ~140 nm immediately after HPT processing and also after further annealing at 423 K. Conversely, it is shown that annealing at temperatures above 473 K leads to a substantial decrease in the hardness values as well as a sharp increase in the grain size of the material previously processed by HPT. In addition, detailed EBSD analysis revealed the formation of a bi-modal distribution of grains after annealing at temperatures from 623 to 773 K, and this becomes more uniform with increasing temperatures.

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“…Therefore, an analysis of texture evolution during annealing of SMC iron is important for studying its thermal stability. Similar investigations of fcc metals are currently underway [16], while data for bcc metals are not available in the literature.…”

Section: Introductionmentioning

confidence: 99%

Effect of microcrystallites formed by deformation on the growth and orientation of grains during recrystallization of iron

Воронова¹,

Degtyarev²,

Чащухина³

et al. 2017

LoM

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Changes of an ultradispersed structure in deformed iron after annealing have been studied. Ultradispersed structures of two different types, cellular and submicrocrystalline (SMC) ones, have been formed in iron by high pressure torsion deformation. The effect of the deformation structure type on the temperature of recrystallization onset, the size of recrystallized grains, and the recrystallization texture has been explored. A comparison of recrystallization of the initial cellular and SMC structures should be made to determine the role of microcrystallites. The recrystallization temperature of iron with an SMC structure is 200 to 250°С lower than that of iron with a cellular structure because of the presence of microcrystallites, which are ready recrystallization nuclei. The recrystallization (annealing at 750°C, 1h) of the cellular structure results in the formation of a coarse-grained structure with an average recrystallized grain size that is by an order of magnitude larger than that after the same annealing of the SMC structure (5 and 180 μm, respectively). The significantly different feature of the SMC structure in contrast to the cellular one is the annealing-assisted formation of a <110> recrystallization texture in it, whereas the annealing of iron with the cellular structure does not cause the formation of a recrystallization macrotexture. An increase in the sharpness of the recrystallization texture correlates with a decrease in the average grain-boundary misorientation angle.

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Microtexture analysis of restoration mechanisms during high pressure torsion of pure nickel

Cited by 48 publications

References 44 publications

Thermal stability and superplastic behaviour of an Al-Mg-Sc alloy processed by ECAP and HPT at different temperatures

Thermal stability and superplastic behaviour of an Al-Mg-Sc alloy processed by ECAP and HPT at different temperatures

Examining the Thermal Stability of an Al-Mg-Sc Alloy Processed by High-Pressure Torsion

Effect of microcrystallites formed by deformation on the growth and orientation of grains during recrystallization of iron

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