Fabrication of the Nb–16Si Alloy Powder for Additive Technologies by Mechanical Alloying and Spheroidization in Electric-Arc Discharge Thermal Plasma

• Published in: Russian journal of non-ferrous metals Vol. 59; no. 6; pp. 671 - 676
• Main Authors: Popovich, A. A., Razumov, N. G., Grigoriev, A. V., Samokhin, A. V., Sufiiarov, V. Sh, Goncharov, I. S., Fadeev, A. A., Sinaiskii, M. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.11.2018; Springer Nature B.V
• Subjects: Alloy development; Alloy powders; Alloy systems; Alloying elements; Alloys; Arc resistance heating; Binary systems; Ceramic; Chemistry and Materials Science; Composite Materials; Densification; Electric arcs; Electric discharges; Gas turbine engines; Hardeners; Heat resistant materials; Intermetallic compounds; Materials Science; Mechanical alloying; Melting points; Metallic Materials; Nickel base alloys; Planetary mills; Plasma; Plasma generators; Refractory; Refractory materials; Refractory metals; Silicides; Silicon; Thermal plasmas; mechanical alloying; spheroidization; spherical powder; thermal plasma; heat-resistant alloy
• ISSN: 1067-8212; 1934-970X
• DOI: 10.3103/S1067821218060160

The development of new, more refractory heat-resistant materials for gas-turbine engines is one of most important problems of modern materials science. This is associated with the fact that nickel superalloys currently used for this purpose have a lower melting point of ~1400°C, which limits their own maximal working temperature by a range of 1100–1150°C. The Ni alloys can be replaced by natural composites, in which refractory metals are a matrix, while their silicides are intermetallic hardeners. Only three “refractory metal–silicon” binary systems manifest stability to the Me 5 Si 3 silicide, notably, Nb 5 Si 3 , Re 5 Si 3 , and W 5 Si 3 . From the viewpoint of a combination of a high melting point and a low density, the Nb 5 Si 3 compound is optimal among other silicides. The use of alloys of the Nb–Si system in additive manufacturing machines is of considerable interest. This work presents the results of experimental investigations into the treatment of the Nb–16 at % Si powder fabricated using mechanical alloying of elemental Nb and Si powders in the thermal plasma flux. The Nb–16Si alloy powder is fabricated by the mechanical alloying of powders of pure elements in a Fritsch Pulverisette 4 planetary mill. The powder spheroidization is performed in a plasma installation based on a discharge vortex-stabilized electric-arc thermal plasma generator. Based on the results of experimental investigations, the principal possibility to perform the plasma spheroidization of particles of the Nb–16Si alloy prepared by mechanical alloying is shown. It is shown that the surface of spheroidized particles is rough and reflects the cast material structure. Three phase components Nb 5 Si 3 , Nb 3 Si, and Nb ss having different optical contrast are revealed in microslices, which is confirmed by X-ray phase analysis.