Strengthening mechanisms in nanostructured high-purity aluminium deformed to high strain and annealed

Kamikawa, Naoya; Huang, Xiaoxu; Tsuji, Nobuhiro; Hansen, Niels

doi:10.1016/j.actamat.2009.05.017

Cited by 581 publications

(308 citation statements)

References 36 publications

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“…For such materials it may be more appropriate to make a distinction between these two different types of boundaries based on the misorientation angle across them, where it is assumed that boundaries with misorientation below a certain critical angle (θ c ) contribute to the strength via dislocation strengthening, whereas boundaries with misorientations higher than θ c contribute to the strength via GB strengthening. According to Refs [34,37], the flow stress can, in this case, be described as:…”

Section: Analysis Of Mechanical Behaviormentioning

confidence: 99%

Microstructure and mechanical properties of nickel processed by accumulative roll bonding

Zhang

Mishin

Kamikawa

et al. 2013

Materials Science and Engineering: A

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A detailed investigation of the microstructure and mechanical properties has been conducted in pure nickel deformed to high strains using accumulative roll bonding (ARB). Samples have been investigated after different numbers of ARB cycles and the results have been compared with data for nickel processed by other deformation techniques, with particular focus on conventional rolling. It is found that the structural evolution in ARB-processed nickel is rapid at low strains followed by a slower evolution as the strain approaches ultrahigh levels. Comparing samples processed by ARB and conventional rolling to an identical nominal strain, the microstructure after ARB is more refined and contains a greater fraction of high angle boundaries. This enhanced refinement is attributed to the geometric accumulation of shear-strain influenced volumes as a result of the ARB process and large-draught rolling conditions. Based on the observations, it is suggested that the key strengthening mechanisms in deformed nickel are grain boundary and dislocation boundary strengthening, and that the strength-microstructure relationship can be expressed by a single parameter equation, σ-σ0 = k2dav-0.5, where k2 is a constant and dav is the average boundary spacing in the deformed microstructure. Abstract: A detailed investigation of the microstructure and mechanical properties has been conducted in pure nickel deformed to high strains using accumulative roll bonding (ARB).Samples have been investigated after different numbers of ARB cycles and the results have been compared with data for nickel processed by other deformation techniques, with particular focus on conventional rolling. It is found that the structural evolution in ARB-processed nickel is rapid at low strains followed by a slower evolution as the strain approaches ultrahigh levels.Comparing samples processed by ARB and conventional rolling to an identical nominal strain, the microstructure after ARB is more refined and contains a greater fraction of high angle boundaries. This enhanced refinement is attributed to the geometric accumulation of shear-strain influenced volumes as a result of the ARB process and large-draught rolling conditions. Based on *Manuscript Click here to view linked References 2 the observations, it is suggested that the key strengthening mechanisms in deformed nickel are grain boundary and dislocation boundary strengthening, and that the strength-microstructure relationship can be expressed by a single parameter equation, σ-σ 0 = k 2 d av -0.5 , where k 2 is a constant and d av is the average boundary spacing in the deformed microstructure.

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Section: Analysis Of Mechanical Behaviormentioning

confidence: 99%

Microstructure and mechanical properties of nickel processed by accumulative roll bonding

Zhang

Mishin

Kamikawa

et al. 2013

Materials Science and Engineering: A

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“…В резуль-тате ИПДК-обработки наблюдается повышение предела прочности и условного предела текучести в ∼ 4 раза, однако пластичность образцов снижается до δ ≈ 18%. Данные результаты хорошо согласуются с результатами работ [2][3][4][11][12][13]15], в которых ИПД образцов Al была выполнена другими методами, такими, например как специальная прокатка (accumulative roll-bonding), рота-ционная ковка, равноканальное угловое прессование. В соответствии с соотношением Холла−Петча [19,20] высокие показатели условного предела текучести об-разцов Al_RT связаны с измельчением зерен в ре-зультате ИПДК-обработки и, как следствие, увеличения объемной плотности ГЗ в структуре.…”

Section: рисunclassified

“…Существенным недостатком ультрамелкозер-нистой (УМЗ) структуры является значительное сни-жение пластичности по сравнению с пластичностью в крупнозернистом (КЗ) состоянии [6]. Для оптимизации прочностных и пластических свойств в последнее время активно проводятся исследования влияния отжига на механические свойства Al [11][12][13][14][15][16]. Однако результаты этих исследований достаточно противоречивы.…”

Section: Introductionunclassified

“…Однако результаты этих исследований достаточно противоречивы. Так, в ря-де работ наблюдалось повышение прочности УМЗ-мате-риалов при отжиге [11][12][13][14]. Например, в работе [11] обнаружено повышение прочности в результате отжига при 423 K высокочистого (99.99 wt.%) и технически чистого (99.2 wt.%) Al, предварительно обработанных специальной прокаткой (accumulative roll-bonding).…”

Section: Introductionunclassified

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Влияние отжига на микроструктуру и механические свойства ультрамелкозернистого технически чистого Al

Мавлютов¹,

Латынина²,

Мурашкин³

et al. 2017

Физика Твердого Тела

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Исследовано влияние отжига на микроструктуру и механические свойства ультрамелкозернистого (УМЗ) технически чистого Al, предварительно подвергнутого интенсивной пластической деформации кручением под давлением. Установлено, что отжиг УМЗ-образцов в диапазоне температур 363-473 K в течение 1 h приводит к повышению условного предела текучести и предела прочности, прирост которых достигает максимального значения (до 50 и 30% соответственно) после отжига при 423 K. Обсуждается ключевая роль неравновесных большеугловых границ зерен в полученном эффекте упрочнения УМЗ-Al путем отжига. Увеличение прочности сопровождается значительным снижением пластичности. Предложен новый подход для улучшения пластичности УМЗ-Al при сохранении высокого уровня прочности. Он заключается во введении дополнительной плотности дислокаций в релаксированную отжигом УМЗ-структуру. Авторы (М.Ю.М. и Р.З.В.) выражают благодарность Министерству образования и науки РФ за финансовую поддержку в рамках проекта N 14.Б25.31.0017. Рентгеноструктурные исследования проведены с использованием оборудования Ресурсного центра научного парка СПбГУ "Рентгенодифракционные методы исследования". DOI: 10.21883/FTT.2017.10.44964.094

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“…22) Hence, the role of the low-angle boundaries on microhardness should be argued also in the present worn iron. To show grain-size dependence of the microhardness, boundary spacing in both the submicron grain and the lowangle boundary regions were measured from the corresponding IPF map, which was obtained prior to the microhardness tests.…”

Section: ¹1mentioning

confidence: 99%

EBSD Analysis of Microstructure Evolution of Pure Iron Subjected to Sliding Wear and Related Change in Vickers Microhardness

Kaneko

Sugimoto

2014

Mater. Trans.

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Sliding wear tests were carried on pure iron to investigate evolution of microstructure below worn surface. After the wear tests, grain boundary formation and lattice rotation were analyzed with electron backscatter diffraction (EBSD) method. In the vicinity of the worn surface, submicron grains separated by high-angle grain boundaries were generated. Below the submicron grain region, dominant microstructures were two kinds of low-angle grain boundaries which were horizontal and inclined to the worn surface, respectively. At deeper area from the worn surface, continuous lattice rotation was detected. To correlate the microstructure and strength, Vickers microhardness was measured over a cross section of the wear-affected zone. In the submicron grain and the low-angle grain boundary regions, the microhardness was proportional to the reciprocal square root of boundary spacing. In the lattice rotation region, we calculated geometrically-necessary (GN) dislocation density from gradient of lattice rotation. The microhardness value in the lattice rotation region showed good correlation with the square root of the GN dislocation density.

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Strengthening mechanisms in nanostructured high-purity aluminium deformed to high strain and annealed

Cited by 581 publications

References 36 publications

Microstructure and mechanical properties of nickel processed by accumulative roll bonding

Microstructure and mechanical properties of nickel processed by accumulative roll bonding

Влияние отжига на микроструктуру и механические свойства ультрамелкозернистого технически чистого Al

EBSD Analysis of Microstructure Evolution of Pure Iron Subjected to Sliding Wear and Related Change in Vickers Microhardness

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