Nikolay G. Razumov; Anatoly A. Popovich; Andrey V. Samokhin; Aleksei V. Grigoriev
Abstract
Spherical Nb-Si powder alloy is a perspective material to manufacture products for the aerospace industry by additive technologies. Nb-16Si (at.%) powder alloy was prepared by mechanical alloying from pure elemental powders using planetary ball mill Fritsch Pulverisette 4. Spheroidization was carried ...
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Spherical Nb-Si powder alloy is a perspective material to manufacture products for the aerospace industry by additive technologies. Nb-16Si (at.%) powder alloy was prepared by mechanical alloying from pure elemental powders using planetary ball mill Fritsch Pulverisette 4. Spheroidization was carried out on plasma generator based on thermal plasma arc generator with vortex discharge stabilization. Experimental results show that plasma spheroidizing of Nb-16Si powders obtained by mechanical alloying is possible. It is shown that after the spheroidization the particle surface is rough which indicates the cast structure of the material. Three phases having different optical contrast are revealed on microsections: Nb5Si3, Nb3Si and Nbss, which is confirmed by X-ray diffraction. It is shown that the main peaks in the X-ray graph after MA correspond to a solid solution of niobium with a cubic lattice and the parameter a = 0.333 nm, as well as niobium silicide Nb5Si3 with a hexagonal lattice (P63/m) a = 0.7536 nm and c = 0.5249 nm. After spheroidization the hexagonal lattice of niobium silicide Nb5Si3 is transformed into a tetragonal lattice (I4/m) with the parameter a = 0.6557 nm and c = 1.186 nm. The other phase components remain unchanged.
Nikolay G. Razumov; Aleksandr S. Verevkin; Anatoly A. Popovich
Abstract
The effect of heat treatment on the structure and magnetic properties of Sm-Fe alloys obtained by mechanical alloying was investigated. The crystallization temperature of Sm2Fe17, an amorphous alloy obtained by mechanical alloying, was determined using differential scanning calorimetry. Based on these ...
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The effect of heat treatment on the structure and magnetic properties of Sm-Fe alloys obtained by mechanical alloying was investigated. The crystallization temperature of Sm2Fe17, an amorphous alloy obtained by mechanical alloying, was determined using differential scanning calorimetry. Based on these results, various samples were annealed at different isothermal holding temperatures, and those with the best magnetic properties were found. Experimental studies show that decreasing the isothermal holding temperature from 750 °C to 630 °C increases magnetic characteristics nearly four times. The saturation magnetization, romance and coercivity of the Sm2Fe17 powder were 121 emu/g, 28.5 emu/g and 800 Oe, respectively.
Anatoly A. Popovich; Nikolay G. Razumov
Abstract
In this work, we investigated the effect of the treatment duration on the phase formation and dissolution of alloying elements in the process of mechanical alloying (MA) of iron with austenite forming elements in the nitrogen-containing atmosphere. The influence of MA parameters on the phase composition ...
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In this work, we investigated the effect of the treatment duration on the phase formation and dissolution of alloying elements in the process of mechanical alloying (MA) of iron with austenite forming elements in the nitrogen-containing atmosphere. The influence of MA parameters on the phase composition of the alloy showed the first of the alloying elements dissolved in the lattice of iron are nickel, then chrome and manganese. According to experimental data, the dissolution proceeds through the formation of a layered composite. Also the features of the nanocrystalline structure of powder materials Fe-18Cr-8Ni-12Mn-N, synthesized by mechanical alloying are presented. The nanocrystalline structure of these alloys consists of two structural components: grain-crystallites and grain boundary regions. Such type of structure corresponds to the Gleiter model. Dimensions of nanocrystals are in range from 6 to 20 nm.