Physical metallurgy and mechanical properties of transition-metal Laves phase alloys

• Published in: Intermetallics 2000-09, Vol.8 (9-11), p.1119-1129
• Main Authors: Liu, C.T, Zhu, J.H, Brady, M.P, McKamey, C.G, Pike, L.M
• Format: Article
• Language: English
• Subjects: A. Laves phases; ALLOYS; B. Mechanical properties at ambient temperature; B. Mechanical properties at high temperatures; D. Defects: point defects; LAVES PHASES; MATERIALS SCIENCE; MECHANICAL PROPERTIES; PHYSICAL METALLURGY
• ISSN: 0966-9795; 1879-0216
• DOI: 10.1016/S0966-9795(00)00109-6

This paper provides a comprehensive review of the recent research on the phase stability, point defects, and fracture toughness of AB2 Laves phases, and on the alloy design of dual-phase alloys based on a soft Cr solid solution reinforced with hard XCr2 second phases (where X=Nb, Ta and Zr). Anti-site defects were detected on both sides of the stoichiometric composition of NbCr2, NbCo2, and NbFe2, while they were observed only on the Co-rich side of ZrCo2. Only thermal vacancies were detected in the Laves phase alloys quenched from high temperatures. The room-temperature fracture toughness cannot be effectively improved by increasing thermal vacancy or reducing stacking fault energy through control of phase stability. Microstructures, mechanical properties, and oxidation resistance of dual-phase alloys based on Cr–NbCr2, Cr–TaCr2, and Cr–ZrCr2 were studied as functions of heat treatment and test temperature at temperatures to 1200°C. Among the three alloy systems, Cr–TaCr2 alloys possess the best combination of mechanical and metallurgical properties for structural use at elevated temperatures.