Properties of high-temperature alloys of the system Ni-Al-Nb with a unidirectional eutectic structure

Journal Article · Fri Mar 01 04:00:00 EST 1985 · Met. Sci. Heat Treat. Met. (Engl. Transl.); (United States)

OSTI ID:6269578

Toropov, V M; Bondarenko, IU A

The effects of directional solidification with eutectic crystallization of the gamma- and delta-phases of the ternary alloy Ni-Al-Nb were examined in an attempt to provide better ductility and high temperature oxidation resistance. Specimens of the system examined, Ni-Ni3Al-Ni3Nb, were studied for the variations in the microstructural characteristics in response to variation in the chemical compositions. The Bridgman method was used to effect directional solidification. A unidirectional structure composed of alternating gamma- and delta-phases was observed in specimens with 21-23 percent Nb and 2.0-2.5 percent Al directionally solidified in thermal gradients of 70-80 deg/cm and at a crystallization rate of 0.3-0.4 mm/min. Stress cracking tests of the unidirectional materials yielded a time to failure of 14-24 hr at 1100 C with a 120 MPa stress. The time to failure was extended to 69-81 hr by adding 2-4 percent Cr. 8 references.

• OSTI ID: 6269578
• Journal Information: Met. Sci. Heat Treat. Met. (Engl. Transl.); (United States), Journal Name: Met. Sci. Heat Treat. Met. (Engl. Transl.); (United States) Vol. 26:9-10; ISSN MHTRA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
ALUMINIUM ALLOYS
CHEMICAL REACTIONS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
EUTECTICS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
MATERIALS
MICROSTRUCTURE
NICKEL ALLOYS
NIOBIUM ALLOYS
OXIDATION
PHASE TRANSFORMATIONS
SOLIDIFICATION