Bimodal size distributions of {gamma}{prime} precipitates in {und Ni}-Al-Mo. 1: Small-angle neutron scattering

Journal Article · Fri Sep 01 04:00:00 EDT 1995 · Acta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-7151(95)00043-U· OSTI ID:105987

Sequeira, A D; Calderon, H A; Kostorz, G ^[1]; Pedersen, J S ^[2]

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1. ETH Zuerich (Switzerland). Institut fuer Angewandte Physik
2. Risoe National Lab., Roskilde (Denmark). Dept. of Solid State Physics

The evolution of the microstructure during the decomposition of two {und Ni}-Al-Mo alloys with a bimodal size distribution of precipitates was studied using small-angle neutron scattering. Precipitate size distributions and space correlations of the bimodal precipitate ensemble were determined by model fitting of the scattering curves. The correlation effects between the precipitates were taken into account by the locally-monodisperse (LMD) hard-sphere model. This model assumes that the ensemble of precipitates have their positions correlated with their sizes, being locally monodisperse. The form factors were used according to the shape of the precipitates, spherical in the case of alloy I, Ni-8.8Al-9.6Mo (at.%) (isotropic system), and cuboidal for alloy II, Ni-9,5Al-5.4Mo (anisotropic system). To characterize the microstructure of the two alloys a set of characteristic parameters (e.g. volume fraction, average radii, precipitate number density, etc.) were obtained using relations between the moments {ovr r{sup n}} of the size distribution N(r). The model proved particularly suited to characterize the isotropic system. In the case of the anisotropic system it was insensitive to changes of the size distribution N(r) during aging.

• OSTI ID: 105987
• Journal Information: Acta Metallurgica et Materialia, Journal Name: Acta Metallurgica et Materialia Journal Issue: 9 Vol. 43; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGING
ALUMINIUM ALLOYS
CORRELATED-PARTICLE MODELS
HARD-SPHERE MODEL
INTERMETALLIC COMPOUNDS
MICROSTRUCTURE
MOLYBDENUM ALLOYS
NICKEL BASE ALLOYS
PARTICLE SIZE
PRECIPITATION
SHAPE
SMALL ANGLE SCATTERING