Kinetics of coarsening by the ledge mechanism

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A theoretical study has been made of the coarsening kinetics of an ensemble of cubes by the ledge mechanism. In addition to the usual capillarity variables, these kinetics were found to vary with the inter-ledge spacing and with the Jones-Trivedi parameter, α, which varies with the concentration gradient in front of a ledge. Considerable manipulation is required to effect a reasonable accounting of the effects upon coarsening kinetics of the variation of α with average particle size, ā, because of the complicated nature of this dependency. It is found that an a ̄2~ t dependence is approximated at small particle sizes and an a ̄3~ t relationship develops at larger sizes. These relationships are the same as those obtained by Wagner and by Lifshitz and Slyozov for quite different coarsening mechanisms. The present analysis was shown to be consistent with the detailed experimental data of Ardell and Nicholson on the coarsening kinetics of Ni3Al cubes. © 1979.

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Acta Metallurgica