Qualitative evaluation of the effect of morphology, spatial distribution and coherent interfaces on the coarsening kinetics and size distribution of particles during Ostwald ripening

ABSTRACT

By exploiting the simple structure of the recently developed Multi-Particle model of Ostwald ripening based on pairwise interactions, the effect of extra factors affecting the coarsening process, such as the morphology of particles, the topology of their spatial distribution and the presence of elastic fields surrounding coherent precipitates, is analysed from a qualitative viewpoint.

Two observables disclose the presence of deviations with respect to the behaviour of a system of spherical and incoherent precipitates: the absolute value of the kinetic coarsening constant, together with its evolution with the volume fraction, and the shape of the asymptotic particle size distribution (PSD) for a given volume fraction of second phase.

By using a parametrised ‘rounded cube’ ideal solid it is shown that, as the shape of precipitates flattens, the coarsening constant decreases reaching in some condition values as low as about 20% that of a system of spheres with the same fraction.

Consequently, the curve of the relative kinetic constant with the volume fraction has a slower increase above 0.7 compared to spherical particles and this permits to explain accurately the experimental data on dense systems in the whole range of volume fractions.

It is also shown how the shape of the PSD is influenced by regular arrangements of particles in the space and by interfacial stresses in the matrix surrounding coherent precipitates. In both cases the model predicts a sharpening of the PSD, whose shape tends to become more symmetrical and somehow similar to that of the classical LSW theory.

KEYWORDS:

• Ostwald ripening
• particle size distribution
• particle morphology
• coherent interfaces

Disclosure statement

No potential conflict of interest was reported by the author.