Theoretical prediction and experimental comparison for eutectic growth of Al2O3/GdAlO3 faceted eutectics

Ultra-fine Al2O3/GdAlL3 eutectics with eutectic spacing of 193 +/- 20 nm are directionally solidified by laser floating zone melting process. When the solidification rate increases from 2 m/s to 400 m/s, the morphology transition from Chinese script irregular eutectic to rod-like regular eutectic is found. To predict the growth behaviour of A1203/GdA103 eutectic, the solute diffusion coefficient D1., which exhibits significant influence on eutectic growth, is determined to be 6 x 10-10 m(2)/s. Then, the eutectic microstructures as a function of solidification rate are well predicted by modified Magnin-Kurz model and Jackson-Hunt model, both for Chinese script irregular eutectic and rod-like regular eutectic, respectively.