Coarsening Ostwald ripening

L. Ratke and P.W. Voorhees, Growth and Coarsening Ostwald Ripening in Material Processing (Engineering Materials), Springer, 2002. 

Lorenz Ratke, and Peter W. Voorhees. Growth and coarsening Ostwald ripening in material processing. Berlin Springer, 2002. 

A further problem is possible if the reinforcements are very small. Coarsening of the particles or whiskers may occur driven by Ostwald ripening, in which large particles grow through diffusional transport at the expense of smaller ones. This can be minimized by choosing matrices in which the reinforcement elements have very low solid solubilities and diffusion coefficients. Platelets, however, have been shown to be more resistant to coarsening than particles or whiskers. 

The interaction among the clusters via the common diffusion held leads in general to a coarsening of the clusters with time t. One denotes this by Ostwald ripening [58,96] (see Sec. HID). According to the Lifshitz-Slyozov theory [58] on this process, the typical cluster radius R increases as... 

Coarsening of fine precipitates kept in the mother liquor for protracted time was observed in numerous instances the number of very fine particless in the precipitate decreased in time, and the volume of several large particles simultaneously grew. This effect, after 1899, was frequently referred to as Ostwald ripening. 

C. Wagner Theory for the Coarsening of Solid Precipitates Caused hy Ostwald Ripening. Z. Elektrochem. 65, 581 (1961). 

Note 2 Representative mechanisms for coarsening at the late stage of phase separation are (1) material flow in domains driven by interfacial tension (observed in a co-continuous morphology), (2) the growth of domain size by evaporation from smaller droplets and condensation into larger droplets, and (3) coalescence (fusion) of more than two droplets. The mechanisms are usually called (1) Siggia s mechanism, (2) Ostwald ripening (or the Lifshitz-Slyozov mechanism), and (3) coalescence. 

The coarsening data of Chai (1974) using hydrothermal experiments show that (r) is roughly proportional to f, consistent with coarsening controlled by mass transfer. The proportionality depends on the type of solution, as well as temperature. Many other experimental data also show this relation. That is, Ostwald ripening is often controlled by mass transfer instead of interface reaction. 

S.C. Hardy and P.W. Voorhees. Ostwald ripening in a system with a high volume fraction of coarsening phase. Metall. Trans., 19A(11) 2713-2721, 1988. 

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