Centrifugal SHS Metallurgy of Cast Co-Cr-Fe-Ni-Mn High-Entropy Alloys Strengthened by Precipitates Based on Mo and Nb Borides and Silicides

• Published in: Physical mesomechanics 2021-12, Vol.24 (6), p.692-700
• Main Authors: Sanin, V. N., Ikornikov, D. M., Golosova, O. A., Andreev, D. E., Yukhvid, V. I.
• Format: Article
• Language: English
• Subjects: Borides; Chemical precipitation; Chemical reactions; Chromium; Classical Mechanics; Cobalt; Combustion; High entropy alloys; High temperature; Intermetallic compounds; Iron; Manganese; Materials Science; Mechanical properties; Metal matrix composites; Metallurgy; Microstructural analysis; Microstructure; Molybdenum; Niobium; Physics; Physics and Astronomy; Precipitates; Refractory metals; Silicides; Silicon; Solid solutions; Solid State Physics; Structural members; Synthesis
• ISSN: 1029-9599; 1990-5424
• DOI: 10.1134/S1029959921060072

A promising approach to the development of advanced metallic materials is based on a fundamentally new concept of avoiding the use of the main component but mixing several metal elements simultaneously. Such multicomponent alloys are called high-entropy alloys, the most studied of which is the Co-Cr-Fe-Ni-Mn alloy with attractive mechanical properties. The single-phase fcc structure is stable in this alloy, which allows it to be used as a “model” high-entropy alloy or a single-phase multicomponent solid solution. This paper is the first to experimentally evaluate the possibility of synthesizing strengthened high-entropy alloys with the basic system (Co-Cr-Fe-Ni-Mn) and strengthening precipitates based on borides and silicides of refractory metals (Mo and Nb), formed in situ during the combustion of thermite-type SHS systems. The microstructural analysis of the synthesized NiCrCoFeMn alloys with the complex modifying Mo(Nb)-Si-B additive showed that, at a higher content of the additive, the microstructure of the synthesis products exhibits the high-entropy alloy matrix and precipitates of new structural elements based on borides and silicides of refractory metals (Mo and Nb). The morphology and concentration of such precipitates depends on the concentration of the additive in the green mixture. The strengthening precipitates are of endogenous origin as they are formed in situ during SHS and are the result of chemical reactions occurring both directly in the combustion wave and during cooling of the high-temperature melt of the synthesis products. Control of SHS processes opens up new possibilities for the formation of metal-matrix composites based on high-entropy alloys.