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The development of modern technics is limited by the physical and mechanical characteristics of the produced alloys, properties of which are often determined and enhanced by introduced alloying components. One of the alloying elements that have been very actively introduced in recent years is nitrogen. As a rule, alloying with nitrogen is carried out by ferroalloys, less often by gaseous nitrogen, which has significant advantages. In the processes of special electrometallurgy, alloying with nitrogen can be performed using, for example, nitrogen-containing plasma. Such a method may be feasible in the production of powder metal by spraying the ingot with nitrogen-containing plasma. It is known that performance properties of the products made of powder metal are significantly higher than those of cast metal. This served as a stimulus for investigating the properties of a product obtained from nitrided powder alloy EP741NP. In this work, a study of changes in the chemical composition, microstructure and microhardness of EP741NP alloy samples was carried out. The studied material was nitrided metal powders made on a plasma centrifugal spraying (PREP) unit and ingots from granules obtained by hot isostatic pressing (HIP). The chemical composition of the obtained samples was determined by wave dispersion X-ray fluorescence spectrometry. In order to study the microstructure of metal powders and ingots, the methods of scanning electron microscopy with EDXS were used. Microhardness of the samples was assessed using a microhardness tester by the Vickers method. The analysis of gas impurities was carried out on a gas analyzer. It is shown that nitriding of heat-resistant nickel alloy EP741NP is possible at the stage of metal powder production, without significant loss of alloying components and a sharp change in chemical composition. An increase in microhardness of the obtained nitrided samples was noted in comparison with the initial one.

Increase in metal operational properties is ensured by introduction of a certain set and amount of alloying elements into it. These elements include nitrogen, the interest in which is constantly growing. As many works have shown, nitriding with gaseous nitrogen is used, among other things, in plasma-arc remelting. The data is given on metal alloying with nitrogen at the stage of obtaining granules and powders. However, the latter process requires further study. The process of obtaining nitrogen-containing metal microgranules from EP741NP alloy by plasma centrifugal spraying was studied in this work. Metal powders are obtained by melting the end of a rotating workpiece with a stream of ionized gas (mixture of gases). The technology makes it possible to obtain nitrogen-alloyed fine metal powders of multicomponent spherical alloys with a minimum number of satellites that do not differ in size and chemical composition. Investigation of the nitriding rate is of great interest, especially in the production of powder metal. One of the parameters that affect the degree of metal saturation with nitrogen is time spent by liquid melt under nitrogen-containing plasma and crystallization time of the metal drop. The paper presents a technique that allows one to quantify the role of these parameters on the absorption of nitrogen by the metal during powder production. It is known that the kinetic parameters of the nitriding process are determined by the contact area of ​​two metal – gas phases. In the case of obtaining a powder, this parameter depends on the size of a powder speak. In this connection, the paper presents a calculation method that allows estimating the average fractional composition of metal powders depending on a number of technological factors. The obtained values ​​were compared with the data of semi-industrial heats. It is shown that the fractional composition of microgranules depends on the rotation speed and diameter of the workpiece being remelted, the density of the alloy, and the force of surface tension. It was established that with an increase in the rotation frequency of the consumable electrode, it is possible to achieve a decrease in the fineness of metal powders.

Аннотация. Развитие современной техники лимитируется физико-механическими характеристиками выплавляемых сплавов, свойства которых зачастую определяются и повышаются за счет вводимых легирующих компонентов. К одному из легирующих элементов, весьма активно внедряемому в последние годы, следует отнести азот. Как правило, легирование азотом осуществляется ферросплавами, реже газообразным азотом, имеющим существенные преимущества. В процессах спецэлектрометаллургии легирование азотом можно проводить, используя, например, азотсодержащую плазму. Такой способ может быть осуществим и при получении порошкового металла за счет распыления заготовки азотсодержащей плазмой. Известно, что эксплуатационные свойства изделий из порошкового металла значительно выше, чем из литого. Это служило стимулом изучения свойств изделия, полученного из азотированного порошкового сплава ЭП741НП. В работе проведено исследование изменения химического, фазового состава, микроструктуры и микротвердости образцов сплава ЭП741НП. В качестве исследуемого материала использовались азотированные металлические порошки, изготовленные на установке плазменного центробежного распыления и слитки из гранул, полученные методом горячего изостатического прессования. Элементный состав полученных образцов определяли методом волнодисперсионной рентгенофлуоресцентной спектрометрии. С целью исследования микроструктуры металлопорошков и слитков использовали методы сканирующей элект ронной микроскопии с энергодисперсионным микроанализатором. Микротвердость изучаемых образцов определяли на микротвердомере методом Виккерса. Анализ газообразующих примесей проводили на газоанализаторе фирмы Leco модели Rhen-602 и TC-600. Показано, что азотирование жаропрочного никелевого сплава ЭП741НП возможно на стадии производства металлического порошка без существенной потери легирующих компонентов и резкого изменения химического состава. Отмечено повышение микротвердости полученных азотированных образцов в сравнении с исходным (литым) состоянием.

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