Microstructure and Properties of Aluminum-Containing Refractory High-Entropy Alloys
- 2.1k Downloads
A new metallurgical strategy, high-entropy alloying (HEA), was used to explore new composition and phase spaces in the development of new refractory alloys with reduced densities and improved properties. Combining Mo, Ta, and Hf with “low-density” refractory elements (Nb, V, and Zr) and with Ti and Al produced six new refractory HEAs with densities ranging from 6.9 g/cm3 to 9.1 g/cm3. Three alloys have single-phase disordered body-centered cubic (bcc) crystal structures and three other alloys contain two bcc nanophases with very close lattice parameters. The alloys have high hardness, in the range from H v = 4.0 GPa to 5.8 GPa, and compression yield strength, σ 0.2 = 1280 MPa to 2035 MPa, depending on the composition. Some of these refractory HEAs show considerably improved high temperature strengths relative to advanced Ni-based superalloys. Compressive ductility of all the alloys is limited at room temperature, but it improves significantly at 800°C and 1000°C.
KeywordsIntermetallic Phasis Atomic Radius Lave Phase TiZr Refractory Element
Discussions with Drs. D. Dimiduk, H. Fraser, J. Miller, J. Tiley, S.L. Semiatin, and G. Viswanathan are appreciated. This work was supported through the Air Force Research Laboratory Director’s fund and through the Air Force on-site contract no. FA8650-10-D-5226 operated by UES, Inc., Dayton, OH.
- 9.J.K. Tien and T. Caulfield, Superalloys, Supercomposites and Superceramics (London, U.K.: Academic Press, 1989).Google Scholar
- 10.G. Krauss, Steels: Processing, Structure and Performance (Materials Park, OH: ASM International, 2005).Google Scholar
- 17.M.Y. Demeri, Advanced High Strength Steels (Materials Park, OH: ASM International, 2013).Google Scholar
- 18.Inconel Alloy 718. http://www.specialmetals.com/documents/Inconel%20alloy%20718.pdf. Accessed 21 July 2014.
- 19.M. Kaufman, Superalloys-84 (Fifth International Symposium), (Warrendale, PA: TMS, 1984) pp. 43–52.Google Scholar
- 20.J.R. Kattus, Aerospace Structural Metals Handbook, Mar-M247 (West Lafayette, IN: Purdue Research Foundation, 1999), pp. 1–8.Google Scholar
- 24.T.B. Massalski and H. Okamoto, Binary Alloy Phase Diagrams, 2nd ed. (Materials Park, OH: ASM International, 1990).Google Scholar