Morphological Stability of a Particle Growing by Diffusion or Heat Flow

摘要: The stability of the shape a spherical particle undergoing diffusion‐controlled growth into an initially uniformly supersaturated matrix is studied by supposing expansion, harmonics, infinitesimal deviation from sphericity and then calculating time dependence coefficients expansion. It assumed that pertinent concentration field obeys Laplace's equation, assumption whose conditions validity are discussed in detail often satisfied practice. A dispersion law found for rate change amplitude various harmonics. shown sphere stable below unstable above certain radius Rc, which just seven times critical nucleation theory; analogous conclusions obtained solidification problem. results used to discuss nonspherical forms.