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The coarsening of particles dispersed in a solution was found by Ostwald in 1900. Then, the following cubic law between mean radius (r-) and annealing time (t) was established by Lifshitz-Slyozov and Wagner in 1961. It should be noted,however,that the above equation is valid in the coarsening of B particles in A-B solution.Therefore,some modification is necessary in the case of multi-component materials.For instance,the coarsening of (Fe,Cr)aCb in γFe-M-C matrix is described s folows;According to Eq.(2),the coarsening rate of M23C6 in heat-resistant steel(9%Cr~1%W-0.1%C)depends on the diffusion rate of Cr,because.However,experimental data inform us that the rate-de-termining element is not Cr but W as shown in Fig.1The problem is solved by modifing the formula of M23C6 from (Fe,Cr,W)23C6to Fe4(Cr,W)19C6 in this case (Fig.2).Consequently,the coarsening equation is expressed as follows.
The coarsening of particles dispersed in a solution was found by Ostwald in 1900. Then, the following cubic law between mean radius (r-) and annealing time (t) was established by Lifshitz-Slyozov and Wagner in 1961. It should be noted, However, that the above equation is valid in the coarsening of B particles in AB solution. Beforefore, some modification is necessary in the case of multi-component materials. For instance, the coarsening of (Fe, Cr) aCb in γFe-MC matrix According to Eq. (2), the coarsening rate of M23C6 in heat-resistant steel (9% Cr ~ 1% W-0.1% C) depends on the diffusion rate of Cr, inform us that the rate-de-termining element is not Cr but W as shown in FIG. 1 The problem is solved by modifing the formula of M23C6 from (Fe, Cr, W) 23C6to Fe4 (Cr, W) 19C6 in this case Fig.2) .Consequently, the coarsening equation is expressed as follows.