Producing a gradient-composition nanocrystalline structure on nitrided surfaces of invar-type Fe-Ni alloys using megaplastic deformation

Шабашов, В. А.; Борисов, С. В.; Литвинов, А. В.; Kataeva, N. V.; Afanas'ev, S. V.; Титова, С. Г.

doi:10.1134/s0031918x14090117

Cited by 4 publications

(15 citation statements)

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“…The possibilities to control and govern atomic redistribution by means of large plastic deformation have found further realization in the works on deformation-induced dissolution and precipitation of disperse interstitial phases in austenitic and ferritic steels [10][11][12][21][22][23]32,33].…”

Section: The Formation Of Submicrostructure In High-nitrogen Fe-cr-n mentioning

confidence: 99%

“…To execute large plastic deformation and to control the conditions of the experiment, along with practically important external actions, such as milling in a ball mill (BM) [9][10][11], frictioning at friction treatment [21,32,33], and reducing at rolling [15], the high pressure torsion (HPT) method (of pressure torsion) in Bridgman anvils [12][13][14][15][16][17][18][19][20][21]23] was used. The method of HPT permits (i) the creation of high degrees of true deformation (ε~ 9) without the failure of samples and (ii) the control of the degree, rate, and temperature of deformation.…”

Section: Introductionmentioning

confidence: 99%

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Atomic Order and Submicrostructure in Iron Alloys at Megaplastic Deformation

Шабашов

Сагарадзе

Козлов

et al. 2018

Metals

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The subject of the present review consists of summing up our previous results on the study of the relaxation of structure along the way (i) of atomic redistribution—in the form of short-range clustering in binary iron alloys—induced by megaplastic deformation (i.e., of super large value), and (ii) of the dissolution and precipitation of disperse nitrides and carbides in steels and intermetallics in ageing alloys. Within the capacity of the main method of executing megaplastic deformation, along with the practically important milling in ball mills and friction-providing external action, we employed high pressure torsion (HPT) in Bridgman anvils, which permitted the control of the degree, rate, and temperature of deformation action. At the local level of two nearest neighbors (one or two coordination shells in relation to an iron atom) we studied atomic mass transfer, stipulated by generation of a large number of point defects of deformation origin, and conducted a comparison with a case of irradiation by high-energy electrons. We established a change in the direction of phase transformations, as well as anomalous acceleration of the ordering and precipitation of disperse phases upon altering the temperature (T < 0.3Tmelt) and rate of deformation (from 2 × 10−2 to 8 × 10−2 s−1). We also demonstrated the possibility of regulating the ultra-fine-grained structure with solid–solution strengthening and dispersion hardening.

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Section: The Formation Of Submicrostructure In High-nitrogen Fe-cr-n mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Atomic Order and Submicrostructure in Iron Alloys at Megaplastic Deformation

Шабашов

Сагарадзе

Козлов

et al. 2018

Metals

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“…При ИП-азотировании в поверхностном слое формируются нитриды, распределение которых неоднородно и ограничено по глубине в несколько микрон. В работах [1,2] было обнаружено увеличение глубины распределения нитридов в матрице азотированных сталей с использованием большой холодной пластической деформации фрикционным воздействием и сдвигом под давлением (СД) в наковальнях Бриджмэна. Объяснение этого было дано на основе механизма циклических фазовых деформационноиндуцированных переходов растворение-выделение нитридов [3].…”

Section: Introductionunclassified

“…Объяснение этого было дано на основе механизма циклических фазовых деформационноиндуцированных переходов растворение-выделение нитридов [3]. Деформация СД приводит к растворению нитридов CrN, сформированных в поверхностных слоях матрицы, насыщая структуру дефектами [1,2]. Последующий отжиг вызывает диффузию азота в объем образца на глубину, существенно превосходящую исходный азотированный слой.…”

Section: Introductionunclassified

“…Последующий отжиг вызывает диффузию азота в объем образца на глубину, существенно превосходящую исходный азотированный слой. Предложенная де- [1][2][3]5]. Азотирование проводилось в азотно-водородной смеси в диапазоне давлений 0,4…1,3 ГПа.…”

Section: Introductionunclassified

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Increasing the depth of the nitrided layer in the surface of austenitic alloys using friction treatment

Шабашов¹,

Korshunov²,

Литвинов³

et al. 2016

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In the Fe-12Cr-30Ni and Fe-15Cr-38Ni ion-plasma nitrided austenitic alloys the depth of the surface, gradient in concentration and phase composition, has been increased from 5 µm to 20 µm using dry sliding friction and high-pressure torsion in Bridgman anvils. The treatment is based on deformation-induced chromium nitride dissolution-precipitation cyclic phase transitions. As a result of 1 h nitriding at 500 C, a nitrogen solution in the Fe-Ni-Cr-N matrix and disperse nitrides of chromium CrN and iron Fe 4 N are formed in the alloy surface layers. Subsequent dry sliding friction or high-pressure torsion leads to nanostructuring, deformation-induced dissolution of chromium and iron nitrides, as well as to the mechanical alloying of the surface and the inner nonnitrided alloy layers. Besides, in the deformed austenitic matrix secondary chromium nitrides are formed. With additional 2 h annealing at 600 C, the additional exit of nitrogen from the austenitic Fe-Ni-Cr-N solid solution occurs, with the preferential formation of Cr 2 N nitride and the increase of the volume (depth) of the alloy matrix changed in terms of its structure and composition. The reverse sequence, that is, preliminary friction and subsequent nitriding of the surface, does not noticeably increase the depth of the nitrided layer. It is explained by the accelerated migration of non-equilibrium grain boundaries in the surface nanostructured by friction, which reduces the time required for complete recrystallization to much less than the time of 1 h nitriding at 500 C. The result of fast recrystallization is the slight effect of fast diffusion in the surface nanostructured by friction.

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