SYMPOSIA PAPER Published: 01 January 1991

Evaluating Clustering of Second-Phase Particles


Procedures for assessing the homogeneity of second-phase particle distributions were reviewed and some of these were used to assess the distribution of Sulfides in a free-machining stainless steel (transverse vs. longitudinal planes) and primary carbides in a superalloy. An image amendment procedure was shown to provide the best description of clustering with direct determination of the number of clusters per mm2, the number of particles per cluster, and the number or area fraction percentages of particles in clusters. All can be obtained as a function of the interparticle spacing. One can also determine the size of clusters and the distance between clusters, if desired. The theoretical nearest-neighbor spacing, nns, for a random Poisson distribution, based on NA, provides an upper limit for image dilation. Based on this work, a cluster should contain at least three particles with interparticle spacings less than the nns. Recommendations for further improvements to the method were made.

Author Information

Vander Voort, GF
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Developed by Committee: E04
Pages: 242–267
DOI: 10.1520/STP17270S
ISBN-EB: 978-0-8031-5162-8
ISBN-13: 978-0-8031-1399-2