Abstract
Generally, most of polycrystalline ceramics have been made from fine powders via their shape forming and sintering, not via melt/casting, because melt/solidified ceramics would crack during cooling. In order to prevent the accumulation of residual stresses, we have tried to make the samples by rapid solidification of the eutectic systems. In the ternary systems of Zirconia(Hafnia)-Alumina-YAG, we have succeeded to fabricate nano-structured bulk ceramics by just simple solidification of the melt. The mixed powders were melted into a globule with 3 - 5 mm diameter by an arc-imaging furnace, then cooled rapidly. The spherical samples were transparent, no cracking and consisted of 20-100 nm size crystals: Zirconia-Hafnia-Alumina-YAG. Zirconia-Hafnia-Alumina-ABOperovskite system would give transparent amorphous phases, which can be charged into nanocrystalline bulk composites by appropriate annealing. Those ceramic nano-composites can be applied for wide areas; structural, functional, and coating materials.
