Partial reduction of NiAl{sub 2}O{sub 4} -- Mechanism and the influence of doping
- Cornell Univ., Ithaca, NY (United States). Dept. of Materials Science and Engineering
- Los Alamos National Lab., NM (United States). Ceramic Science and Technology Group
Metal-ceramic microstructures were formed in situ by partial reduction of the spinel compound NiAl{sub 2}L{sub 4}. At 1,300 C the reduction reaction passed through an intermediate stage involving the formation of Ni and metastable defect spinel phases, before the appearance of the equilibrium phases, Ni + {alpha}-Al{sub 2}O{sub 3}. At 1,100 C, depending on the reduction time, the products of the reduction reaction were Ni and the metastable defect spinel for less than 24 hours; Ni + {theta}-Al{sub 2}O{sub 3} for 24--48 hours; and Ni + {alpha}-Al{sub 2}O{sub 3} for 144--168 hours. The effects of dopants, such as Cr{sub 2}O{sub 3}, MgO, TiO{sub 2} and Y{sub 2}O{sub 3}, on the reduction mechanism and kinetics were examined and shown, in the case of TiO{sub 2}, to have a controlling influence. A reduction reaction mechanism is proposed.
- Sponsoring Organization:
- Department of the Air Force, Washington, DC (United States)
- OSTI ID:
- 479307
- Report Number(s):
- CONF-951155-; ISBN 1-55899-301-0; TRN: IM9725%%68
- Resource Relation:
- Conference: Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 27 Nov - 1 Dec 1995; Other Information: PBD: 1996; Related Information: Is Part Of Thermodynamics and kinetics of phase transformations; Im, J.S. [ed.] [Columbia Univ., New York, NY (United States)]; Park, B. [ed.] [Georgia Inst. of Tech., Atlanta, GA (United States)]; Greer, A.L. [ed.] [Cambridge Univ. (United Kingdom)]; Stephenson, G.B. [ed.] [Argonne National Lab., IL (United States)]; PB: 697 p.; Materials Research Society symposium proceedings, Volume 398
- Country of Publication:
- United States
- Language:
- English
Similar Records
Interfacial chemical stability during diffusion bonding of Al{sub 2}O{sub 3}-fibers with Ni{sub 3}Al- and NiAl-matrices
In-situ formation of ductile phase toughened ceramics by partial reduction reactions in the Ni-Al-O system