An in situ X-ray diffraction study of precipitation from a supersaturated solid solution: The. gamma. prime precipitate in a Ni-12. 5 at. % Al alloy

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Acta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-7151(90)90096-Y· OSTI ID:6960569

Marsh, C; Chen, H ^[1]

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1. Univ. of Illinois, Urbana (United States)

An in situ X-ray diffraction study of the precipitation reaction of a supersaturated solid solution single crystal of Ni-12.5 at.% Al alloy was performed for moderately high temperatures. The diffusion-control coarsening model of Lifshitz and Slyozov is used to interpret the results of measuring the rate constants determined from the growth of the average particle size and volume fraction of the {gamma}{prime} phase precipitate as derived from the line width and integrated intensity of the superlattice reflection, respectively. Both the diffusion coefficient and the interfacial energy between the matrix and precipitates were experimentally determined for temperatures in the range of 550-700C. The interfacial energies are reasonable when compared with literature values and they seem to indicate a decrease with increasing temperature. The diffusion coefficients yield consistent yet lower values when compared to results for Ni-self diffusion in single crystals, and to polycrystalline measurements of Al diffusion in Ni at comparable temperatures. An enhanced diffusion is observed at 550C and possible explanations are offered. In addition, the coarsening rate was measured to be different for two crystallographic directions at the same temperature. This difference is suggested to be related to the precipitate morphology change from sphere to cuboid evidenced in many Ni-base alloys.

• DOE Contract Number: AC02-76ER01198
• OSTI ID: 6960569
• Journal Information: Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 38:11; ISSN 0956-7151; ISSN AMATE
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOY SYSTEMS
ALLOYS
ALUMINIUM ALLOYS
BINARY ALLOY SYSTEMS
COHERENT SCATTERING
CRYSTALS
DIFFRACTION
DIFFUSION
DISPERSIONS
ENERGY
INTERFACES
MIXTURES
MONOCRYSTALS
MORPHOLOGICAL CHANGES
NICKEL ALLOYS
NICKEL BASE ALLOYS
PHASE STUDIES
PRECIPITATION
SATURATION
SCATTERING
SEPARATION PROCESSES
SOLID SOLUTIONS
SOLUTIONS
SUPERSATURATION
TEMPERATURE EFFECTS
X-RAY DIFFRACTION