Modeling and experimental study of the interface morphology and growth kinetics of fibrous eutectic solidification

Experimental studies of fibrous eutectic growth in succinonitrile-camphor reveal that models of the stable range of interfibrous spacings must incorporate the dynamic effects and the instability of the growth front of the fibrous phase, which determines the fineness and regularity of the microstructures. An analytical mathematical model for fibrous eutectic growth has been developed and compared with the experimental results. The selected wavelength scales obey λ = √d₀l_sf (l_s/l_t), where d₀, l_s, l_t are the capillary, diffusion, and thermal lengths, respectively. While only at a relatively high growth rate or steep temperature gradient, the scaling law λ²V = constant is fulfilled. It is found that the selected band of interfibrous spacings is very narrow. This means that the interfibrous spacing is almost unique at a given growth rate and a fixed temperature gradient. The effects of convection on the interfibrous spacing selection and fibrous phase instability of short wavelength perturbations have also been investigated. These studies reveal that the controlled solidification of a fibrous eutectic produces a very fine and regular microstructure.