Effect of the Carbon Content on the Structure and Mechanical Properties of a High-Temperature Carbide-Hardening Niobium–Molybdenum Alloy

• Published in: Russian metallurgy Metally Vol. 2022; no. 5; pp. 520 - 527
• Main Authors: Gnesin, I. B., Karpov, M. I., Prokhorov, D. V., Gnesin, B. A., Stroganova, T. S., Zheltyakova, I. S., Vnukov, V. I., Ryabenko, E. I., Svetlov, I. L.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.05.2022; Springer Nature B.V
• Subjects: Alloying elements; Carbon content; Chemistry and Materials Science; Creep strength; Creep tests; Crystal structure; Electron beams; Eutectic alloys; High temperature; Materials Science; Mechanical properties; Metallic Materials; Molybdenum base alloys; Niobium carbide; Room temperature; Zone melting; microstructure; strength; niobium carbide; niobium; phase analysis; creep; molybdenum
• ISSN: 0036-0295; 1555-6255; 1531-8648
• DOI: 10.1134/S0036029522050044

The elemental, phase, and structural state of Nb–Mo–C alloys with equiatomic metal contents and 15, 20, 25, and 30 at % C are studied after electron-beam zone melting. In the alloy containing 15 at %, a fine microstructure, which is typical of eutectic alloys, forms; as the carbon content increases, primary carbide crystals appear in the alloy structure. The main carbide phase in all alloys is found to be an NbC-based carbide rather than an Nb 2 C-based carbide. The component distribution between the phases is studied as a function of the average alloy composition. The results of short-time strength tests of alloy specimens at room temperature and at 1500°C and also their high-temperature bending creep tests are presented. The 100-h creep strength maximum for the alloys is shown to be 200–300 MPa at 1500°C ( = 200–300 MPa).