Design of quaternary Ir-Nb-Ni-Al refractory superalloys

Journal Article · Sat Jan 01 04:00:00 EST 2000 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-000-0063-9· OSTI ID:20014054

Yu, X H; Yamabe-Mitarai, Y; Ro, Y; Harada, H

The authors propose a method for developing new quaternary Ir-Nb-Ni-Al refractory superalloys for ultra-high-temperature uses, by mixing two types of binary alloys, Ir-20 at. pct Nb and Ni-16.8 at. pct Al, which contain fcc/L1{sub 2} two-phase coherent structures. For alloys of various Ir-Nb/Ni-Al compositions, the authors analyzed the microstructure and measured the compressive strengths. Phase analysis indicated that three-phase equilibria--fcc, Ir{sub 3}Nb-L1{sub 2}, and Ni{sub 3}Al-L1{sub 2}--existed in Ir-5Nb-62.4Ni-12.6A1(at.pct) (alloy A), Ir-10Nb-41.6Ni-8.4Al(at.pct)(alloy B), and Ir-15Nb-20.8Ni-4.2Al(at.pct)(alloy C) at 1,400 C; at 1,300 C, three phase equilibria--fcc, Ir{sub 3}Nb, and Ni{sub 3}Al--existed in alloys A and C and four-phase equilibria--fcc, Ir{sub 3}Nb, Ni{sub 3}Al, and IrAl-B2--existed in alloy B. The fcc/L1{sub 2} coherent structure was examined by using transmission electron microscopy (TEM). At a temperature of 1,200 C, the compressive strength of these quaternary alloys was between 130 and 350 MPa, which was higher than that of commercial Ni-based superalloys, such as MarM247 (50 MPa), and lower than that of Ir-based binary alloys (500 MPa). Compared to Ir-based alloys, the compressive strain of these quaternary alloys was greatly improved. The potential of the quaternary alloys for ultra-high-temperature use is also discussed.

• Research Organization: National Research Inst. for Metals, Ibaraki (JP)
• OSTI ID: 20014054
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 1 Vol. 31; ISSN MMTAEB; ISSN 1073-5623
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
COMPRESSION STRENGTH
HEAT RESISTING ALLOYS
IRIDIUM ALLOYS
MICROSTRUCTURE
NICKEL ALLOYS
NIOBIUM ALLOYS