Transformation to Ni[sub 5]Al[sub 3] in a 63. 0 at. pct Ni-Al alloy

Journal Article · Thu Dec 31 23:00:00 EST 1992 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02669606· OSTI ID:6209600

Khadkikar, P S ^[1]; Locci, I E; Michal, G M ^[2]; Vedula, K ^[3]

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1. Therm-O-Disc, Inc., Mansfield, OH (United States)
2. Case Western Reserve Univ., Cleveland, OH (United States) NASA Lewis Research Center, Cleveland, OH (United States)
3. Iowa State Univ., Ames (United States)

Microstructures in a 63 at. pct Ni-Al alloy, produced by a powder metallurgy process, have been investigated in detail in as-quenched and aged (823 to 923 K) conditions. The parent L1[sub 0] martensite plus B[sub 2] NiAl microstructure in the as-quenched state transformed nearly completely to the orthorhombic Ni[sub 5]Al[sub 3] phase upon aging at 823 K for 720 hours. The volume fraction of Ni[sub 5]Al[sub 3] formed as a function of aging time at 823 K was observed to obey cellular reaction kinetic behavior. The specimens aged at 823 K for short times indicated that nucleation of the Ni[sub 5]Al[sub 3] phase occurred preferentially at grain boundaries. Transmission electron microscopy (TEM) observations of short-time aged specimens revealed a complex microstructure consisting of short-range ordered domains of Ni[sub 2]Al in a matrix of 7R martensite, in addition to new variants of 3R martensite and Ni[sub 5]Al[sub 3]. Aging at 873 and 923 K for 720 hours produced a stable two-phase microstructure consisting of NiAl and Ni[sub 5]Al[sub 3]. A quantitative phase analysis was carried out to calculate the (NiAl + Ni[sub 5]Al[sub 3])/Ni[sub 5]Al[sub 3] phase boundary locations. The measured lattice parameters of Ni[sub 5]Al[sub 3] formed at 823, 873, and 923 K indicated an increase in tetragonality of the phase with increasing nickel content.

• OSTI ID: 6209600
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 24:1; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
AGING
ALLOYS
ALUMINIUM ALLOYS
CARBON ADDITIONS
COHERENT SCATTERING
DATA
DIFFRACTION
ELECTRON MICROSCOPY
EXPERIMENTAL DATA
GRAIN BOUNDARIES
INFORMATION
INTERMETALLIC COMPOUNDS
IRON ALLOYS
MARTENSITE
METALLURGY
MICROSCOPY
MICROSTRUCTURE
NICKEL ALLOYS
NICKEL BASE ALLOYS
NUMERICAL DATA
PHASE STUDIES
PHASE TRANSFORMATIONS
POWDER METALLURGY
QUENCHING
SCATTERING
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION