The development of spatial correlations during Ostwald ripening: A test oftheory

The coarsening of solid-Sn particles in a Pb-Sn liquid was studied under mi crogravity conditions. Spatial correlation functions were measured on plane sections in a low-volume fraction system undergoing Ostwald ripening. The correlation functions changed with time in a way that indicated that the mi crostructure initially consisted of clusters of particles and evolved into one which was more dispersed. The model by Akaiwa and Voorhees (AV) was use d to study the effect of spatial correlations on the ripening process. We f ound that the initially highly correlated structure had no observable effec t on the evolution of particle size distributions, but did have an effect o n the coarsening rate of the system. Specifically, we determined that a str ucture consisting of clusters of particles coarsened faster than a system w ith a random, spatial arrangement of non-overlapping particles. We also fou nd that the approach of the microstructure towards the steady-state regime could be monitored more sensitively using spatial correlations rather than using particle size distributions. The spatial correlations and the particl e size distributions measured from the experiment agreed well with those ca lculated from the AV simulations using the initial experimental correlation s and size distribution. (C) 2000 Acta Metallurgica Inc. Published by Elsev ier Science Ltd. Ail rights reserved.