Discontinuous precipitation in a Ni-In alloy studied by analytical field ion microscopy

Journal Article · Thu May 01 04:00:00 EDT 1997 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(96)00302-3· OSTI ID:509149

Geber, G P; Kirchheim, R ^[1]

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1. Univ. Goettingen (Germany). Inst. fuer Metallphysik

Discontinuous precipitation (DP) in a Ni-7.5 at.% In alloy has been studied by means of atom probe field ion microscopy (APFIM). The morphology of the lamellar microstructure and the growth kinetics of the decomposition reaction have been investigated by optical and scanning electron microscopy (LM, SEM). A back polishing method has been developed to prepare APFIM specimens in a systematic manner for transmission electron microscopy (TEM), in order to obtain a definite inclination of different interfaces in the tip apex for subsequent analysis of their chemical composition. APFIM results of the Ni- and In-concentration across the interfaces are presented. Based on the APFIM results it is possible to distinguish between the theoretical description of the concentration profiles given by the models of Cahn and Hillert. It is shown by both FIM images and concentration depth profiles that the {alpha}/{beta}-interface has a thickness of about 0.5 nm. In addition it is shown for the first time that the concentration across a {beta}-lamella is not constant. This experimental finding was used to develop a generalization of Cahn`s model on discontinuous precipitation including the solute flux within the interface between {beta} and the parent phase {alpha}{sub 0}.

• OSTI ID: 509149
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 5 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
INDIUM ALLOYS
INTERFACES
KINETICS
LAMELLAE
MICROSTRUCTURE
MORPHOLOGY
NICKEL BASE ALLOYS
PRECIPITATION