Some oxide eutectic materials, such as sapphire/YAG, display an intricate “Chinese script” microstructure which strongly influences properties such as mechanical strength. We used the micro pulling-down technique to grow fibers of a series of such materials at rates over 20 mm/min, giving a uniform microstructure with a characteristic size as low as 150 nm. Bulk and surface characteristics of this microstructure were investigated by electron and atomic force microscopy. Smaller microstructure size gave higher tensile strength at 1500°C. Annealing of the fibers produced some coarsening of the microstructure, but increased the strength at lower temperatures.