Ordering reactions in an Ni-25Mo-8Cr alloy

Journal Article · Mon Apr 01 04:00:00 EST 1996 · Acta Materialia

DOI:https://doi.org/10.1016/1359-6454(95)00258-8· OSTI ID:230797

Kumar, M; Vasudevan, V K ^[1]

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1. Univ. of Cincinnati, OH (United States). Dept. of Materials Science and Engineering

The transformations from short- to long-range order in Haynes{reg_sign} Alloy 242, a nominal Ni-25Mo-8Cr (in wt%) alloy, during isothermal aging at temperatures between 550 and 750 C are reported using microhardness measurements, and optical and transmission electron microscopy. Aging below the critical transformation temperature ({approximately} 775 C) led to considerable hardening; this hardening was associated with the formation of a very high volume fraction of Ni{sub 2} (Mo,Cr) domains/precipitates. The transformation from short- to long-range order was observed to proceed by a mechanism of continuous ordering at temperatures {le} 700 C, whereas at temperatures (750 C) close to the critical temperature a first order nucleation and growth mechanism appeared to be operative. The sequence of transformations are correlated with the associated diffraction effects and discussed in terms of theoretical formulations and experimental observations of other studies.

• OSTI ID: 230797
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 4 Vol. 44; ISSN XZ504Y; ISSN 1359-6454
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
AGING
CHROMIUM ALLOYS
GAS TURBINE ENGINES
HARDENING
INTERMETALLIC COMPOUNDS
MATERIALS
MICROHARDNESS
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NUCLEATION
OPTICAL MICROSCOPY
ORDER-DISORDER TRANSFORMATIONS
PRECIPITATION
TRANSMISSION ELECTRON MICROSCOPY