The kinetics of the mechanical alloying of Fe and Cr powder mixtures with Cr contents of 20–48 at % has been studied by Mössbauer spectroscopy, X-ray diffraction analysis, and temperature measurements of dynamic magnetic susceptibility. It has been found for the first time that the processes of mechanical alloying differ for initial mixtures with chromium contents of 30 at % or more and contents of less than 30 at %. For the first case, the unidirectional dissolution of Cr in Fe is observed through the whole process of mechanical alloying of the mixture in a planetary ball mill. For the second case, the dissolution of Cr in Fe is observed at the beginning stage of milling; however, after milling for 2 h (tmil), the reverse process, namely, the dissolution of Fe in Cr is likely to dominate. The mechanically alloyed samples are characterized by inhomogeneous Cr and Fe concentration distribution in powder particles, in particular at a Cr concentration in the initial mixture of more than 30 at %.

Cu + Cr 3 C 2 composites have been produced using the mechanical alloying of the elemental components, followed by severe plastic deformation by torsion, magnetic-pulse pressing, and electric-pulse plasma sintering. The composites are studied using X-ray diffraction and light and electron microscopy, as well as measurements of the hardness, density, and electric conductivity. Magnetic-pulse pressing at a temperature of 500°C makes it possible to produce volume nanocomposites with a homogeneous distribution of dispersed carbides over the copper matrix, which has a density of 96%, a Vickers microhardness of 4.6 GPa, a Rockwell hardness of 69 HRA , and an electric conductivity of 19% IACS units. Using electric-pulse plasma sintering at a temperature of 700°C, composites with the nanostructured copper matrix, which contains carbide inclusions and consists of domains surrounded by a layer of nearly pure copper, have been produced. These composites have a density of 88%, a Vickers microhardness of 4.0 GPa, a Rockwell hardness of 58 HRA , and electric conductivity of 26% IACS units.

Methods of X-ray diffraction, differential thermal analysis, and measurements of the dynamic magnetic susceptibility have been used to investigate the sequence of phase transformations upon the mechanical alloying of a mixture of powders of the initial components of the composition (Fe 0.93 Cr .07 ) 75 C 25 . It has been shown that, at later stages of mechanical alloying, the phase composition is determined by the conditions of the dynamic equilibrium between the crystalline and amorphous phases. A change in the conditions of mechanical alloying leads to a shift in this equilibrium and to a change in the phase composition of the alloy. A comparison of carbide formation in the Fe–C system upon the mechanosynthesis, tempering of martensite, the saturation of iron with carbon from the gaseous medium, the quenching of the melt, and the sputtering deposition of films has been performed. Some general regularities have been established, from which it follows that an important role in phase formation upon the mechanosynthesis, just as in other abovementioned processes, is played by the thermally activated phenomena.

В рамках энергетического подхода методами рентгеновской дифракции и зондовой мессбауэровской спектроскопии проанализированы результаты исследования механически сплавленных бинарных систем состава Si(Al, Mg, Cr)9957Fe1. Установлено, что начальной стадии механического сплавления предшествует “подготовительный” этап, связанный с достижением зернами основного компонента (элемента) критического размера Lcr, после чего реализуется собственно процесс сплавления. Показано, что при рассмотрении кинетики начальной стадии сплавления универсальной характеристикой является максимум производной dN/d(lg D), соответствующий размеру зерна Lmax = 17 нм независимо от типа основного компонента (N – выход продуктов реакции, D – доза механической энергии). Установлена определяющая роль химического взаимодействия основного элемента с Fe в кинетике механического сплавления, возрастающая в ряду Mg, Al, Si, Cr. Дано феноменологическое объяснение линейной зависимости N(D) при линейной зависимости удельной поверхности границ зерен от дозы механической энергии.

Исследовано влияние легирующего элемента Cr на структуру, параметры сверхтонких взаимодействий, магнитные свойства нанокомпозитов составов (Fe1 - xCrx)75C25, где х = 0.01–0.10, полученных механическим синтезом c последующим отжигом. Установлено, что легирование хромом понижает коэрцитивную силу, намагниченность насыщения и температуру Кюри цементита. В то же время легирование хромом повышает стабильность цементита к термическим воздействиям.

С помощью мёссбауэровских методов и магнитных измерений исследовано формирование фаз в процессе механосинтеза в шаровой планетарной мельнице нанокомпозита (Fe0.93Cr0.07)75C25 с последующими отжигами при различных температурах. Показано, что на начальном этапе механосинтеза образуется аморфная Fe–C-фаза, а затем аморфная Fe–Cr–C-фаза, из которой в процессе дальнейшего механосинтеза формируется легированный цементит. Обнаружено, что изменение исходного состава (Fe0.93Cr0.07)75C25-порошков до 5 мас. % за счет продуктов намола с размольных шаров, изготовленных из стали ШХ-15, практически не оказывает влияние на фазовый состав, удельную намагниченность насыщения и коэрцитивную силу образцов, отожженных в течение 1 ч при 800°C.

Solid state reactions during mechanical alloying (MA) in a binary mixture of powdered Cr and Fe-57 in atomic ratio of 99: 1 have been studied using Fe-57 Mossbauer spectroscopy, X-ray diffraction and Auger spectrometry. The proposed model of MA includes formation of Cr(Fe)(x)O-y oxides at the contact places of Cr and Fe particles, formation of nanostructure with simultaneous dissolution of the oxides, penetration of Fe atoms along grain boundaries in close-toboundary distorted zones of interfaces in a substitutional position, formation of the substitutional solid solution of Fe in Cr in the body of grains. It was shown that the increase in the BCC lattice parameter on increasing the milling time is due to the dissolution of oxides and formation of interstitial solid solution of O in Cr. There were established substantial differences in consumption of BCC Fe in a Mg -> Al -> Si -> Cr sequence due to the major role of chemical interaction of Mg(Al, Si, Cr) with Fe.

X-ray diffraction, Mössbauer spectroscopy, and measurements of the dynamic magnetic susceptibility have been used to investigate phase states of the Fe72.6C24.5O1.1N1.8 alloy at different stages of the mechanosynthesis (MS) in a planetary ball mill. The introduction of impurities of O and N into an Fe75C25-based alloy changes the sequence of the formation of phases during MS: instead of Fe3C, the Fe7C3 carbide is first to be formed. The processes of phase formation in the alloy preliminarily subjected to MS have unidirectional nature upon the continuation of the MS and upon annealings and are determined by the interaction of the alloy components with one another under the effect of the accumulated excess energy. The phase compositions of the MS alloys depend on the conditions of the dynamic equilibrium between the crystalline and amorphous phases.

The application of double-layer substrate from 56 Fe nonresonance isotope and 57 Fe ultrafine layer allows one to use Mössbauer spectroscopy to investigate the interfacial area in the “iron-nanoscale polymer film” system. The anodic dissolution of iron substrate is used to investigate the interfacial layer by X-ray photoelectron spectroscopy.

Введение добавок Ga, V и Mn (Mx,y = 0, 5, 10 ат. %) в упорядоченный сплав Fe65Al35 Fe65 - yAl35 - xMx,y направлено на изучение общих и частных особенностей температурного (5–300 К) и полевого (до 5 Tл) поведения магнитных характеристик этих сплавов. В работе обсуждается возможность интерпретации совокупности результатов магнитометрии и мёссбауэровской спектроскопии в рамках эффектов магнитного фазового расслоения и на основе моделей локализованных магнитных моментов.