THE USE OF NIOBIUM IN THE DEVELOPMENT OF AIR-CAST NICKEL-CHROMIUM ALLOYS FOR HIGH-TEMPERATURE SERVICE
Difficulty is frequently encountered in air-casting nickel-base creep- resisting alloys hardened with titanium and aluminum, because of the formation and entrapment of oxide films. Exploration of alternative hardening mechanisms has shown that the addition of 3 to 4 at.% niobium to a low-carbon nickel- chromium-base alloy containing 20 to 30 at.% chromium can result in marked precipitation-hardening at 750 and 850 deg C. Further, stressrupture tests at 815 deg C have revealed that a useful level of creep-resistance is thus obtained. A conspicuous feature of these alloys is that when niobium is added to the molten nickel - chromium-base charge, the normal oxide skin is immediately replaced by a mobile, apparently clean surface, which is retained throughout the subsequent casting procedure. This observation suggests that alloys of this type would be particularly suitable for aircasting. A systematic study was made of the effects of combined additions of niobium, molybdenum, and tungsten to a low-carbon nickel- -chromiun-base alloy and, from the results obtained, a composition was developed (EPE 10) that can readily be cast in air. The alloy has properties similar to those of the titanium- and aluminum-hardened alloy Nimocast 90. (auth)
- Research Organization:
- International Nickel Co. (Mond), Ltd., Birminghan, Eng.
- NSA Number:
- NSA-16-015216
- OSTI ID:
- 4793496
- Journal Information:
- J. Inst. Metals, Journal Name: J. Inst. Metals Vol. Vol: 90
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ALUMINUM
ALUMINUM ALLOYS
CARBIDES
CASTING
CHROMIUM ALLOYS
CLEANING
CREEP
FAILURES
FILMS
HIGH TEMPERATURE
LIQUID METALS
MATERIALS TESTING
MECHANICAL PROPERTIES
METALS, CERAMICS, AND OTHER MATERIALS
MOLYBDENUM
NICKEL ALLOYS
NIOBIUM ALLOYS
OXIDES
PLANNING
PRECIPITATION
STABILITY
STANDARDS
STRESSES
SURFACES
TEMPERING
TITANIUM
TITANIUM ALLOYS
TUNGSTEN
USES