Uniaxial tensile plastic deformation and grain growth of bulk nanocrystalline alloys

Fan, G. J.; Fu, Lin; Choo, Hahn; Liaw, Peter K.; Browning, Nigel D.

doi:10.1016/j.actamat.2006.06.016

Cited by 130 publications

(80 citation statements)

References 52 publications

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“…Although grain growth could occur through this process, defects were not released and the grain size was not greater than micron scale. [16] Therefore, the strain-free microstructure and grain size greater than a micron in the CTD sample indicate that the former reason is not plausible.…”

Section: Resultsmentioning

confidence: 99%

“…There are two explanations for the coarse grains that appeared in the ultrafine-structured CTD sample: in situ grain growth during deformations [16,17] and recrystallization. [18] The former (grain growth) is attributed to non-uniform grain boundary mobility of ultrafine materials, which leads to sub-grain growth and local inhomogeneous distribution of stress, and to subsequent grain rotation for sub-grain agglomeration.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

Ahn

Lee

Kang

et al. 2016

Metall Mater Trans A

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PURE copper was compressed at high strain rates (over~3 9 10 3 s À1 ) under liquid nitrogen. This deformation resulted in bi-modal microstructures of ultrafine grains and abnormally grown micro grains, and in greater hardness (by~30 Hv) than room-temperature, dynamically deformed copper. This bi-modal microstructure is attributable to partial recrystallization at room temperature, activated by high-energy states and by twins generated at high ZenerHollomon parameter conditions. This result demonstrates a new approach for producing bi-modally structured materials.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

Ahn

Lee

Kang

et al. 2016

Metall Mater Trans A

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“…[2,7,14,18,20,21,24,31] Noteworthy, however, is the fact that most published theoretical and experimental papers related to stressinduced grain growth focus on single-phase materials and as a result, material systems containing secondphase particles have been rarely reported. Moreover, although many materials that contain a high level of solute segregation at GBs are selected as model materials for studies of stress-induced grain growth, [5,9,11,32,33] the influence of solute atoms segregated at GBs on stress-induced grain growth has been investigated only in very limited cases. [24,34] For example, in a related study, [34] the effect of O segregated at GBs in nanocrystalline Al films produced by magnetron sputtering on stress-induced grain growth during uniaxial tensile testing was investigated via TEM and atomprobe tomography (APT).…”

Section: Stress-induced Grain Growth Has Attractedmentioning

confidence: 99%

“…Furthermore, published experimental studies of stress-induced grain growth predominantly address phenomena that occur at room temperature (RT) [1,[3][4][5][6][7]9,[11][12][13] and cryogenic temperature. [10] In contrast, stress-induced grain growth at elevated temperatures has been investigated only in few studies, [2,8] which hinders our basic understanding of the aforementioned commercially important plastic deformation approaches, including extrusion, rolling, forging, etc.…”

Section: Stress-induced Grain Growth Has Attractedmentioning

confidence: 99%

“…Recent studies on stress-induced grain growth involve in situ [1][2][3][4][5][6][7][8] and ex situ [9][10][11][12][13] transmission electron microscopy (TEM) analysis, optical microscopy observations [14,15] , and molecular dynamic (MD) simulations. [16][17][18][19][20][21][22][23][24] Related published theoretical and experimental results reveal that there are two roles that an externally applied stress plays during grain growth:…”

Section: Stress-induced Grain Growth Has Attractedmentioning

confidence: 99%

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Erratum to: Stress-Induced Grain Growth in an Ultra-Fine Grained Al Alloy

Lin

Wen

Liu

et al. 2014

Metall Mater Trans B

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This paper reports on a study of the stress-induced grain growth phenomenon in the presence of second-phase particles and solutes segregated at grain boundaries (GBs) during high-temperature deformation of an ultra-fine grained (UFG) Al alloy synthesized via the consolidation of mechanically milled powders. Our results show that grain growth was essentially inhibited during annealing at 673 K (400°C) in the absence of an externally applied stress, whereas in contrast, grain growth was enhanced by a factor of approximately 2.7 during extrusion at 673 K (400°C). These results suggest that significant grain growth during hot extrusion was attributable to the externally applied stresses stemming from the state of stress imposed during extrusion and that the externally applied stresses can overcome the resistance forces generated by second-phase particles and solutes segregated at GBs. The mechanisms underlying stressinduced grain growth were identified as GB migration and grain rotation, which were accompanied by dynamic recovery and possible geometric dynamic recrystallization, while discontinuous dynamic recrystallization did not appear to be operative. His research interests include the synthesis and behavior of nanostructured and multi-scale materials with particular emphasis on processing fundamentals and physical behavior; thermal spray processing of nanostructured materials; spray atomization and deposition of structural materials; high temperature-high pressure atomization processes; mathematical modeling of advanced materials and processes; and additive manufacturing. He has published 515 journal and 225 conference publications on topics ranging from nanomaterials to extremely strong aluminum alloys. Prof. Lavernia has delivered more than 150 invited lectures and seminars in over 17 countries. He

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An Insight into Machining of Thermally Stable Bulk Nanocrystalline Metals

et al. 2018

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Recent advances have enabled the production of nano‐grained metallic alloys with a thermally stable microstructure. Consequently, the production of bulk samples and subsequent machining and testing of standardized test specimens is now a real possibility. Therefore, for the first time, the authors report on the in‐depth characterization and machinability of bulk nanocrystalline materials. In particular, this study addresses the feasibility of machining and to what extent, if any, the microstructure is altered due to the high stresses and temperature incurred during machining. Toward that goal, a series of copper–tantalum nanocrystalline threaded cylindrical tensile samples are machined from extruded rods. Advanced characterization techniques, such as transmission electron microscopy, are employed which indicated that the grain size of the Cu–Ta alloy was further reduced by approximately one‐third. This reduction in grain size is quite noteworthy given an estimated total strain of 260% and moderate temperature increase resulting from the machining operation. This unexpected grain refinement is attributed to tantalum‐based nanoclusters dispersed through the matrix which limit grain growth in the initial microstructure during machining. Overall, the authors observe a continuous chip formation and machinability of bulk nanocrystalline materials, which stems from stable nano‐grains and having a near elastically perfectly plastic material behavior.

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Uniaxial tensile plastic deformation and grain growth of bulk nanocrystalline alloys

Cited by 130 publications

References 52 publications

Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

Bi-modal Structure of Copper via Room-Temperature Partial Recrystallization After Cryogenic Dynamic Compression

Erratum to: Stress-Induced Grain Growth in an Ultra-Fine Grained Al Alloy

An Insight into Machining of Thermally Stable Bulk Nanocrystalline Metals

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