Additive technologies are a method of making products of various shapes by adding layers of material in powder using a computer model. The general requirement to powders for additive technology is a spherical particle shape and particle size distribution of high uniformity. Today, the characteristics of powders limit the field of application of additive technologies. Development of new methods for obtaining raw materials for additive technologies will expand the range of used alloys. This paper presents the results of experimental studies of a Nb-Si-based powder alloy, produced by mechanical alloying of Nb, Si, Al, Ti and Cr elemental powders in the flow of thermal plasma. Experimental results show that plasma spheroidizing of Nb-Si-based powders obtained by mechanical alloying is possible. It is shown that after 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.