Fabricating a Novel Intragranular Microstructure for Al(2)O(3)/GdAlO(3) Ceramic Composites

In order to make the embryonic form of intragranular structure, the Al(2)O(3)/GdAlO(3) system was selected due to its excellent mechanical properties. Gd(2)O(3) and Al(NO(3))(3)·9H(2)O were used as the starting materials. A co-precipitation method was used for the preparation of fine ceramics and applied to synthesize the nano-powder of GdAlO(3) firstly. Then, the nano-powder of GdAlO(3) was mixed with the precipitates by the second co-precipitation method. After drying and calcination, the compound powder with eutectic composition (77 mol % Al(3+)—23 mol % Gd(3+)) was fast sintered by using the spark plasma sintering technique. The results revealed that the phases of the sintered samples were Al(2)O(3) and GdAlO(3). The phases showed a homogeneous and interlaced distribution. All the matrix grains were submicron. The sizes of the intragranular structures were between 50 nm and 150 nm. Therefore, the intragranular structure displayed a novel mixture of nanometer–submicron and submicron–submicron types. The different intragranular structures all changed the fracture modes of Al(2)O(3) grains from intergranular fracture to transgranular fracture.