Created in 2004, the high-entropy (HEA) five-component Cantor alloy CoCrFeNiMn is still in the focus of attention of researchers in the field of physical materials science due to a good combination of strength and plastic properties, which open up prospects for its use in various high-tech industries. We performed a brief review of recent publications by domestic and foreign researchers on improving the mechanical properties of the Cantor alloy by alloying with niobium and zirconium, which proved themselves well in alloying traditional alloys. Zirconium alloying leads to a lower melting point due to the formation of eutectic with all elements of the Cantor alloy. Alloying with niobium atoms in the range of 0 – 16 at. % ensures the formation of a volume fraction of the Laves phases and σ–phase up to 42 %, which, in turn, is responsible for a fivefold increase in the yield strength from 202 to 1010 MPa. The work on the joint alloying of the Cantor alloy with Zr + Ti + Y2O3 , Nb + C, Nb + V systems was analyzed. With complex alloying, the mechanical properties are significantly improved. The paper reveals and discusses the physical mechanisms of hardening. Microalloying of 0.2 % Nb alloy with 1.3 % C provides an excellent combination of yield strength (~1096 MPa) and elongation (~12 %) after annealing at 700 °C.

In this work, a coating of a high-entropy alloy CoCrFeNiMn of non-atomic composition is formed on a substrate made of alloy 5083 by the method of wire-arc additive manufacturing (WAAM). The authors investigated the change in microhardness in the contact zone of the coating – substrate system. Using the methods of modern physical materials science, the structural and phase state, defect structure and elemental composition of the coating – substrate system were analyzed. The discovered physical mechanisms contribute to an increase in hardness in the contact zone.

Пятикомпонентные высокоэнтропийные сплавы ВЭС типа сплава CoCrFeNiMn Кантора, обладающие хорошим сочетанием прочностных и пластических свойств и имеющие благоприятные перспективы практического использования, вот уже более четверти века активно исследуются во всем мире. В статье представлен краткий обзор публикаций в основном зарубежных исследователей по поиску направлений изменения, (улучшения) свойств этих сплавов и их практическому применению. Проанализированы теоретические и экспериментальные работы, свидетельствующие о возможности электронных структур в формировании свойств высокоэнтропийных сплавов. Изучение магнитных свойств ВЭС, может дать важную дополнительную информацию об их электронной структуре. На примере ВЭС (CoCrFeMn)1-хNiх, содержащих пять ферромагнитных элементов, прослежена эволюция магнитной природы с изменением температуры. Обращено внимание на необходимость ускорения масштабного практического применения ВЭС. Показаны трудности и сдерживающие факторы практического использования ВЭС и пути их преодоления. В этом направлении проведен анализ публикаций в зарубежной печати о путях создания ВЭС из отходов (лома) машиностроительной и металлургической промышленности. Выполнено сравнение структурно-фазовых состояний и механических свойств ВЭС, изготовленных из чистых составляющих элементов и отходов, содержащих нержавеющую сталь, нихром, кобальтовые сплавы.

With the help of wire arc additive manufacturing, a HEA of AlCrFeCoNi was prepared: of a non-equiatomic composition, on which a B + Cr film with a thickness of ~1 μm was deposited by plasma-assisted RF sputtering. Subsequent processing consisted in electron-beam irradiation of the surface with the following parameters: energy density 20–40 J/cm2, pulse duration 200 μs, frequency 0.3 s–1, number of pulses 3. A quasi-periodic distribution of chemical elements (at. %) 33.4Al; 8.3Cr; 17.1 Fe; 5.4Co; 35.7 Ni is established. It is shown that at the energy density of the electron beam Es = 20 J/cm2, the microhardness increases by a factor of 2, wear resistance by a factor of 5, and the friction coefficient decreases by a factor of 1.3. High-speed crystallization of the surface layer leads to the formation of a subgrain structure with subgrain sizes (150–200 nm). The increase in strength and tribological properties during electron-beam processing is interpreted taking into account the reduction in grain size, the formation of chromium and aluminum oxyborides, and the formation of a solid solution of boron incorporation into the HEA crystal lattice.

Using the technology of wire-arc additive manufacturing (WAAM – wire arc additive manufacture), a high-entropy alloy (HEA) of non-equiatomic composition Al, Cr, Fe, Co, Ni was manufactured. Using the methods of modern physical materials science, an analysis of the elemental and phase composition, defective substructure, mechanical and tribological properties of the HEA surface layer, formed as a result of complex modification, combining the deposition of a film (B + Cr) and irradiation with a pulsed electron beam in an argon medium, was carried out. In the initial state, the alloy has a simple cubic lattice with a lattice parameter of 0.28795 nm; the average grain size of the HEA is 12.3 µm. Chemical elements (at. %) 33.4 Al; 8.3 Cr, 17.1 Fe, 5.4 Co, 35.7 Ni, which form HEA, are distributed quasi-periodically. The irradiation regime was revealed (energy density of the electron beam ES = 20 J/cm2, pulse duration 200 µs, number of pulses 3 pulses, frequency 0.3 s more than 5 times), allowing to increase microhardness (almost 2 times) and wear resistance (more than 5 times), reduce the coefficient of friction by 1.3 times. Regardless of the value of ES, HEA is a single-phase material and has a simple cubic crystal lattice. High-speed crystallization of the surface layer leads to the formation of a subgrain structure (150–200) nm. It is shown that an increase in the strength and tribological properties of HEA is due to a significant (4.5 times) decrease in the average grain size, the formation of particles of chromium and aluminum oxyborides, and the incorporation of boron atoms into the crystal lattice of HEA.

Используя метод проволочно-дугового аддитивного производства (WAAM-wire arc additive manufacturing) на подложке из алюминиевого сплава 5083, было сформировано покрытие из высокоэнтропийного сплава (ВЭС) Mn–Cr–Fe–Co–Ni неэквиатомного состава. Методами сканирующей и просвечивающей электронной микроскопии выполнен анализ структуры, фазового и элементного состава зоны контакта после облучения низкоэнергетическими электронными пучками с параметрами: плотность энергии пучка электронов 30 Дж/см2, длительность импульса 200 мкс, количество импульсов 3, частота следования импульсов 0,3 Гц. Выявлено образование многофазной многоэлементной субмикро- нанокристаллической структуры, сформированной преимущественно в подложке, которая имеет более низкую температуру плавления по сравнению c ВЭС. Установлено, что контактные слои, примыкающие к подложке и покрытию, имеют структуру высокоскоростной ячеистой кристаллизации. В слое, примыкающем к подложке, ячейки образованы твердым раствором магния в алюминии. По границам ячеек выявлены прослойки второй фазы, обогащенные атомами покрытия и подложки. В слое, примыкающем к покрытию, ячейки сформированы сплавом состава 0,17Mg–20,3Al–4,3Cr–16,7Fe–9,3Co–49,2Ni. По границам ячеек выявлены прослойки второй фазы, обогащенные преимущественно магнием и атомами покрытия. Центральная область зоны контакта толщиной ~ 1700 мкм сформирована кристаллитами пластинчатой формы, ее основным элементом является алюминий (≈ 77 ат. %).

Created one of the first and studied more than 20 years ago, high-entropy five-component alloys CoCrFeNiMn (Cantor alloy) and CoCrFeNiAl still attract the attention of researchers in the field of physical materials science due to their possible application in various industries because of their successful combination of strength and plastic properties. To date, a large amount of experimental materials has been accumulated on the ways to control the properties of these alloys. This article reviews the publications of domestic and foreign authors in two areas of improving the properties of these alloys: alloying, precipitation and heat treatment, and the use of CALPHAD phase diagrams. In the first direction, the role of alloying with B, Al, V, Si, Nb is analyzed; γ and γ′ nanoprecipitations, various modes of thermal and deformation processing. It was concluded that it is necessary to conduct experiments on the alloying of HEAs with Zr and Nb, which have proven themselves well in hardening steels. Creation and modification of the properties of five-component HEAs is possible using the CALPHAD computer programs developed for calculating state diagrams. The results of publications on the thermodynamic description of five-component alloys analyzed in the article are confirmed by comparing the phase diagrams with the available experimental data. In one of the analyzed works on the phase formation of five-component HEAs consisting of Co, Cr, Fe, Ni, Al, Mn, Cu, 2436 compositions were considered, which made it possible to determine 1761 variants of reliab­le prediction of the formation of bcc/B2 and fcc phases, bypassing amorphous phases and intermetallic compounds, thereby designing a certain level of mechanical properties. It is shown that the design of a new generation of HEAs is possible based on calculation of the CALPHAD phase diagrams.

Recent publications of foreign and Russian researchers on the influence of niobium microalloying of pearlite steels and high-entropy alloys on their mechanical properties are briefly reviewed. The focus is made on the Nb effect on the microstructure and properties of rail steels and five-component (CoCrFeNiMn) Cantor alloys. The physical mechanisms of strengthening rail steels and high-entropy alloys are revealed and analyzed. An enhanced alloying effect in the case of a combined introduction of Nb + V and Nb + C into the high-entropy alloys is noted and interpreted.

Используя метод проволочно-дугового аддитивного производства (WAAM-wire arc additive manufacturing) на подложке из алюминиевого сплава 5083, было сформировано покрытие из высокоэнтропийного сплава (ВЭС) AlCrFeCoNi неэквиатомного состава (масс %: 15,64 Al; 22,31 Fe; 7,78 Co; 8,87 Cr; 44,57 Ni). Методами сканирующей и просвечивающей электронной микроскопии выполнен анализ структуры, фазового и элементного состава, дефектной субструктуры зоны контакта после облучения низкоэнергетическими электронными пучками с параметрами: плотность энергии пучка электронов 30Дж/см2, длительность импульса 200 мкс, количество импульсов 3, частота следования импульсов 0,3 Гц. Показано, что облучение приводит к фрагментации материала микротрещинами. Выявлено образование многофазной многоэлементной субмикро-нанокристаллической структуры, сформированной преимущественно в подложке, которая имеет более низкую температуру плавления по сравнению ВЭС. Микродифракционным анализом с применением метода темнопольного изображения показано формирование зерен Al3Ni и твердого раствора на основе Al. В объеме зерен Al3Niприсутствуют частицы фазы Fe2Al5, размеры которых изменяются в пределах (35-70) нм. Установлено взаимное легирование покрытия и подложки. Дислокационная субструктура, формирование которой обусловлено термическими напряжениями при облучении электронными пучками, представлена сетками со скалярной плотностью дислокации 2,1·1010 см-2.

Using the technology of cold metal transfer (wire-arc additive manufacturing combined with welding surfacing), a coating is formed on a 5083 alloy substrate with a high-entropy Mn-Fe-Cr-Co-Ni alloy of nonequiatomic composition. Analysis of the structure, elemental composition, and microhardness of the coating-substrate system is carried out using the methods of modern physical materials science. A significant increase (up to 9.9 GPa) in the microhardness of the material is found in the zone of contact between the coating and the substrate. The formation of lamellar inclusions (Al13F4) enriched in coating atoms in the zone of contact between the coating and the substrate is revealed. The high entropy coating in the contact zone has a submicrocrystalline grain-subgrain structure with a crystallite size ranging from 0.5 ^m to 1.1 ^m along the boundaries where nanosized particles of the second phase (Al3Ni) are revealed. The volume of grains contains a dislocation substructure in the form of randomly distributed dislocations or dislocation clusters. The scalar density of the dislocations is (0.8-1.0)-1010 cm-2. An assumption is made about the physical mechanisms of hardening of the material in the "coating-substrate" contact zone. Key words: high-entropy alloy, coating / substrate system, aluminum alloy, elemental and phase composition, microhardness, hardening.

Using scanning and transmission electron microscopy, the analysis of the structure, phase and elemental composition of the contact zone of the system coating (high-entropy FeCrCoNiMn alloy)-substrate (5083 alloy) after electron-beam processing was performed. The formation of a multiphase, multielement submicro- and nanocrystalline structure has been established. The structure of high-speed cellular crystallization in the contact layers adjacent to the coating and substrate is revealed, and the formation of lamellar crystals in the central region of the contact zone is also found. Keywords: contact zone, high-entropy alloy, wire-arc additive manufacturing method, 5083 aluminum alloy, pulsed electron beam, elemental and phase composition, structure.

First created over 20 years, high-entropy five-component alloy CoCrFeNiMn (Cantor alloy) still attracts the attention of researchers in the field of physical materials science because its possible application in various industries due to a successful combination of strength and plastic properties. To date, a large amount of experimental material has been accumulated on how to control the properties of this alloy. This article reviews the publications of Russian and foreign authors in two areas of improving the properties of this alloy: alloying, precipitation and heat treatment and the use of Calphad phase diagrams. In the first direction, the role of alloying with B, Vi, Al, V, Si, Nb is analyzed; nanoprecipitations, various modes of thermal and deformation processing. It is concluded that it is necessary to conduct experiments alloying HEA with Zr and Nb, which have proven themselves well in steels hardening. The creation and modification of the properties of five-component HEA is possible using the Calphad computer software developed for calculating state diagrams. The results of publications on the thermodynamic description of five-component alloys analyzed in the article are confirmed by comparing the phase diagrams with the available experimental data. It is shown that the development of a new generation of HEAs is possible based on the calculation of the Calphad phase diagrams.

Using the wire-arc additive manufacturing method (WAAM) on a 5083 aluminum alloy substrate, a non-equiatomic Mn – Cr – Fe – Co – Ni high-entropy alloy (HEA) coating was formed. By scanning and transmission electron diffraction microscopy we analyzed the structure, phase and elemental composition of the contact zone after irradiation with high-current low-energy electron beams with the following parameters: accelerated electron energy 18 keV, electron beam energy density 30 J/cm 2 , electron beam pulse duration 200 µs, number of pulses 3, pulse repetition rate 0.3 s –1 . Multiphase multielement submicro- and nanocrystalline structures are formed predominantly in the substrate, which has a lower melting temperature compared to HEAs. Mutual doping of the coating – substrate system occurs in the contact layer, which has sinuous boundaries. The contact layers adjacent to the substrate and coating have the structure of high-speed cellular crystallization. In the layer adjacent to the substrate, the cells are formed by a solid solution of magnesium in aluminum. Interlayers of the second phase, enriched in atoms of the coating and substrate, are revealed along the cell boundaries. In the layer adjacent to the coating, the cells are formed by an alloy of composition 0.17Mg – 20.3Al – 4.3Cr – 16.7Fe – 9.3Co – 49.2Ni corresponding to the coating. Interlayers of the second phase, enriched mainly in magnesium and, to a lesser extent, in atoms of the HEA coating, are located along the cell boundaries. Central region of the contact zone with a thickness of ~1700 μm is formed by lamellar crystallites, which indicates the eutectic nature of its formation. Its main element is aluminum (≈77 at. %).

An Al–Fe–Cr–Co–Ni high-entropy alloy (HEA) coating is deposited on a substrate made of 5083 alloy using the cold metal transfer (CMT) technology (wire-arc additive manufacturing (WAAM) in combination with welding surfacing). The HEA alloy has a nonequiatomic composition. The modern physical materials science methods are used to analyze the structure, phase and elemental compositions, defect substructure of the coating–substrate system. It is shown that he elemental and phase compositions, the defect substructure of the coating are dependent on the distance from the zone of contacting the coating and the substrate. The layer with a thickness to 200 µm adjacent to the contact zone contains includes a second phase at the HEA grain boundaries rich in chromium and iron atoms. The microdiffraction analysis shows that these inclusions are Al 8 Cr 5 . It is revealed that nanocrystalline phases Al 2 O 3 and MgAlO with sizes 10–20 nm and a subgrained structure (subgrain size 140–170 nm) form in the zone of mixing the coating and substrate. The structure of the I type is characterized by inhomogeneous distribution of chemical elements in HEA; there are regions of lammelar shape enriched in Cr atoms and the regions of spherical shape enriched Ni, Fe, and Co atoms. Nanosized (NiCo) 3 , Al 4 , and Al 13 Fe 4 particles are arranged along the subgrain boundaries of the system. The physical mechanisms of increasing the material hardness in the coating-substrate contact are discussed.

We have made a brief review of recent foreign and domestic publications, in which the structures, phase compositions, and properties of films and coatings of five-component high-entropy alloys (HEA) on different substrates and the modification of HEA surfaces by different kinds of treatment have been studied. The main methods of film deposition and coatings such as magnetron sputtering, thermal evaporation, laser deposition, and electrodeposition are discussed in the paper. Special attention is paid to the deposition of coatings on stainless steels and titanium alloys. A positive change in the tribological, strength properties, and corrosion resistance of film coatings is seen in a wide temperature range. Possible reasons for the observed effects are discussed considering the role of solid-solution hardening, the formation of a fine-grained structure, and the formation of oxide layers enriched by one of the HEA components. New methods for deposition of HEA coatings and subsequent treatment have been distinguished. The role of niobium and titanium in an increase in the microhardness, wear resistance, and decrease in the friction coefficient of the coatings is considered exemplified by alloying with these elements. The electrolytic polishing, electroerosive machining, mechanical polishing, and combinations thereof are used among the HEA surface treatment methods. In some works, it is suggested to use the powder boriding technique to increase the surface strength and wear resistance of HEA. The studies have been analyzed with respect to electron-beam treatment—one of the promising and highly effective methods of HEA surface hardening.

Using scanning and transmission electron microscopy, the analysis of the structure, phase and elemental composition of the contact zone of the system coating (high-entropy FeCrCoNiMn alloy)-substrate (5083 alloy) after electron-beam processing was performed. The formation of a multiphase, multielement submicro- and nanocrystalline structure has been established. The structure of high-speed cellular crystallization in the contact layers adjacent to the coating and substrate is revealed, and the formation of lamellar crystals in the central region of the contact zone is also found. Keywords: contact zone, high-entropy alloy, wire-arc additive manufacturing method, 5083 aluminum alloy, pulsed electron beam, elemental and phase composition, structure.. Keywords: contact zone, high-entropy alloy, wire-arc additive manufacturing method, 5083 aluminum alloy, pulsed electron beam, elemental and phase composition, structure.

Используя технологию холодного переноса металла (проволочно-дуговое аддитивное производство (WAAM), совмещенное со сварочной наплавкой (СМТ)) на подложке из сплава 5083 сформировано покрытие высокоэнтропийным сплавом (ВЭС) Al-Fe-Cr-Co-Ni неэквиатомного состава. Методами современного физического материаловедения выполнен анализ структуры, фазового и элементного состава, дефектной субструктуры системы «покрытие-подложка». Показано, что элементный и фазовый состав, дефектная субструктура покрытия зависят от расстояния до зоны контакта покрытия и подложки. В слое толщиной до 200 мкм, примыкающем к зоне контакта, выявлено присутствие включений второй фазы на границах зерен ВЭС, обогащенной атомами хрома и железа. Микродифракционным анализом установлено, что это включения Al8Cr5. В зоне перемешивания покрытия и подложки выявлено формирование нанокристаллической фазы Al2O3 и MgAlO размером 10-20 нм и субзеренной структуры (размер субзерен 140-170 нм. Структура 1-го типа характеризуется неоднородным распределением химических элементов ВЭС, выявлены области пластинчатой формы, обогащенные атомами Cr и сферической формы, обогащенные атомами Ni, Fe, Co. По границам субзерен структуры располагаются наноразмерные частицы (NiCo)3, Al4 и Al13Fe4. Высказано предположение о физических механизмах повышения твердости материала в зоне контакта «покрытие-подложка».

Пленочные покрытия на высокоэнтропийные сплавы (ВЭС) являются одним из перспективных и наиболее изучаемых объектов последнего десятилетия. С помощью проволочного дугового аддитивного производства подготовлен ВЭС AlCrFeCoNi: неэквивалентного состава, на который методом плазменно ассистированного ВЧ-распыления была нанесена пленка B+Cr толщиной ~ 1 мкм. Последующая обработка состояла в электронно-пучковом облучении поверхности с параметрами: плотность энергии 20-40 Дж/см2, длительность импульса 200 мкс, частота 0,3 с-1, число импульсов 3. Исследования элементного и фазового состава, состояния дефектной субструктуры системы «пленка-подложка», трибологических и механических свойств проводили методами современного физического материаловедения. Установлено квазипериодическое распределение химических элементов (ат. %) 33,4 Al; 8,3 Сr; 17,1 Fe; 5,4 Co; 35,7 Ni. Показано, что при плотности энергии пучка электронов Еs=20 Дж/см2 микротвердость повышается в 2 раза, износостойкость в 5 раз, коэффициент трения снижается в 1,3 раза. При Еs=20 Дж/см2 поверхность фрагментируется сеткой микротрещин с размерами фрагментов 40-200 мкм. Высокоскоростная кристаллизация поверхностного слоя приводит к образованию субзеренной структуры с размерами субзерен (150-200 нм). Возрастание прочностных и трибологических свойств при электронно-пучковой обработке интерпретировано с учетом снижения размера зерен, формирования оксиборидов хрома и алюминия, образования твердого раствора внедрения бора в кристаллическую решетку ВЭС.

A brief analysis of the work on changing the mechanical properties of the high-energy alloy (HEA) Cantor CoCrFeMnNi in various ways has been performed. The article describes the influence of alloying with aluminum, vanadium, manganese, titanium, silicon, carbon, copper on the hardening of wind turbines obtained by vacuum arc melting, laser melting, arc melting and drip casting, mechanical alloying with subsequent plasma sintering, gas sputtering followed by shock wave and static compaction. It is shown that additives of 2.5 % TiC and 5 % WC significantly improve the tensile strength, but reduce the elongation to failure. The effect of grain size in the range of 4.4 – 155 µm is to increase the tensile strength with a decrease in grain size. Lowering the temperature increases the strength and yield limits for grains of all sizes. Intensive plastic deformation forming nanoscale (~50 nm) grains significantly increases the tensile strength up to 1950 MPa and hardness up to 520 HV. Subsequent isochronous and isothermal annealing allows varying the strength and ductility of wind turbines. The formation of nanostructured-phase states during shock compounding, mechanical alloying and subsequent spark plasma formation significantly increase the tensile strength at room temperature, maintaining excellent plasticity (elongation of approximately 28 %). As one of the methods of modifying the mechanical properties of wind turbines, the authors propose electron-beam processing (EPO). The analysis of the deformation curves of the wind turbine, obtained by the technology of wire-arc additive production, after EPO with an electron beam energy density of 10 – 30 J/cm2, has been carried out; assumptions about the reasons for the decrease in strength and ductility characteristics have been found and substantiated. A comparative analysis of mechanical properties of the Cantor wind turbine obtained by various methods was carried out, and the reasons for discrepancy in the values of strength and plastic parameters were noted.