Calculated growth form

Figure 1. Calculated growth form of the TPA polymorph 1 crystal, Hartman condition. Kitaigorodsld potential functioiL...

Since Equation (3.5) was derived independent of any assumptions regarding the shape of the growth centers, it follows that = E for all growth forms. However, the use of the Avrami approach requires to write Si g t = Ee e. Thus, calculations involving Si g t will evidently require a more complex approach than the use of E directly, and this latter route will be the preference when formulating all forms of growth. 

The above classification scheme can also be applied to two-phase growth ( ). When both phases are low entropy-change the growth kinetics are unimportant and diffusion dominates. This leads to rod or lamellar eutectic growth forms, as shown in Fig. 8. Figure 9 shows the calculated shape of such an interface compared to the observed shape for various growth conditions ( ). These growth forms are common in metallic and some ionic... 

The calculation of the dependence of S upon AT does not seem to have been performed, however, as explained in Sect. 3.3 any theory which has a growth rate proportional to exp — (/ — lmin)/kT will display the correct temperature dependence. As Eq. (3.109) should be dominated by values of / close to lmin the correct functional form for the growth rate follows directly. 

We note that the above equations enable us to calculate p, the fraction of nuclei formed, in terms of a rate constant and the time, t. Note again that ki is the rate constant for nuclei formation whereas k2 is the rate constant for nuclei growth. 

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