Segregation of chemical elements in the volume of powder particles during it's treatment as a method for the production of structurally graded powder materials.

The paper deals with the examples of the use of microsegregation of chemical elements in powder particles of the Inconel 718 heat-resistant alloy for synthesizing on it's basis the "core-shell" type composite metal-ceramic particles in the inductively coupled plasma. A laboratory plasma treatment plant having a quartz plasmatron with a power of 40 kW and a frequency of 5.2 MHz was used. The spheroidization and degassing of the starting material were performed. It was established that, as the powder moved in the plasma flow, the explosive degassing of its particles, with the internal gas pores, took place first, and then the powder melted and spheroidized. It was shown that during the plasma treatment of the Inconel 718 powder in the presence of oxygen, microsegregation of the chemical elements contained in this alloy took place, with the formation of "core-shell" type composite metal-ceramic particles. The metal core consists predominantly of nickel, while the composition of the ceramic shell includes chromium and iron oxides, as well as spinels of the NiCr 2 O 4 and NiFe 2 O 4 types. By varying the oxygen concentration in the plasma, the shell thickness and the core diameter of the composite particle can be changed. The method makes it possible to synthesize metal-ceramic composite powders of the "core-shell" type for additive manufacturing. [Display omitted] • Explosive degassing and spheroidization occurs during powder plasma treatment. • Incorporating oxygen during Inconel plasma treatment forms 'core-shell' particles. • Oxygen concentration in plasma allows to control sizes of the core and shell. • Metal cores of the particles are based on nickel. • Ceramic shell is based on Fe and Cr oxides and spinels of the NiCr2O4 and NiFe2O4. [ABSTRACT FROM AUTHOR]