OBRABOTKAMETALLOV TECHNOLOGY Vol. 26 No. 1 2024 The microhardness testing of the polished specimens was carried out using a Duramin 5 model with the applied load of 50 g and the holding time of 10 s. To achieve average readings, a 10-point measurement mode was selected in longitudinal and cross sections. The studies of the structural and phase state of the specimen were carried out using a JEOL JEM-2100 transmission electron microscope. Results and Discussions Powders with the particle size of 20–64 μm were combined in the weight proportion of Al – 91 wt. %, Si – 8 wt. %, Mg – 1 wt. %, and then subjected to stirring in a ball mill for one hour in the protective atmosphere of argon to prevent the formation of oxides and the undesirable eff ect of oxygen on the structure and phase composition of the resulting powder [20]. Exploratory experiments showed that the time of mechanical alloying equal to 40 and 50 minutes is not enough to obtain a circumspherical shape. Therefore, all further studies were carried out with a powder composition subjected to 60 minute activation. The following is a brief description of the results obtained when working with X-ray diff raction patterns of Al-Mg-Si powder specimens obtained by mechanical stirring in a ball mill working on the “tumbling drum” principle for 1 hour. X-ray diff raction shows the identifi cation of aluminum, silicon and magnesium phases (fi gure 2). The phase composition of aluminum was established as 91 %, that of silicon was established as 8 % and that of magnesium was established as 1 %. Fig. 3 shows scanning electron images of the mixed aluminum, silicon and magnesium powder. The powder composition is a conglomerate of circumspherical particles and irregularly shaped satellites with particle sizes from 1 to 170 μm (fi gure 3 a). The elemental composition of particles is as follows: aluminum (90.3 wt. %), silicon (8.4 wt. %) and magnesium (1.3 wt. %). The enlarged image in fi gure 3, a shows powder particles with a predominantly smooth surface, fi ne grain structure and some fi ne satellite powders partially fused to the surface of the larger particles. The mapping method made it possible to determine the uniform distribution of aluminum powder particles in the form of large and small conglomerates throughout the entire volume of the mixture (fi gure 3, b). From the distribution map it was concluded that aluminum occupies the largest share in the powder mixture. Silicon powder is distributed non-uniformly throughout the volume of the powder mixture in the form of Fig. 2. X-ray diff raction pattern of a specimen of Al-Si-Mg powder obtained by stirring for 1 hour
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