On the meaning of the impingement parameter in kinetic equations for nucleation and growth reactions

摘要: If certain preconditions are met, the Johnson-Mehl-Avrami-Kolmogorov (JMAK) kinetic equation is exactly accurate for nucleation and growth reactions with linear is, at least, a good approximation parabolic growth. These include randomly distributed product phases, isotropic constant equilibrium state. Mechanisms causing deviations from these include: capillarity effect, vacancy annihilation, blocking due to anisotropic It shown that lead modification of overall transformation, which can be approximated well by single equation: $$\alpha = 1 - \left[ {\frac{{\left\langle {k\left\langle T \right\rangle t} ^{n_s } }}{{\eta _i }} + 1} \right]^{ \eta $$ where α fraction transformed, η i impingement parameter, n s k(T) parameters depend on geometry rate. The factors influence parameter discussed.