C-AXIS ALIGNMENT OF YBACUO GRAINS BY CREEP SINTERING

The possibility of aligning the ''c'' axis of YBaCuO grains by deformi ng them during sintering has been investigated for two different comme rcial powders. It is shown that when sintering is performed in the pre sence of a liquid phase, the ceramic deforms substantially at very tow and practically constant stress before exhibiting a regular strain ha rdening stage. When there is just a small amount of liquid phase, the misorientation between the ''c'' axis of the various grains can be as low as 8 degrees, whereas when the liquid phase is too abundant, the 1 23 phase starts decomposing and the material is not textured. At tempe ratures below that of appearance of the liquid phase, deformation dire ctly starts with a long strain hardening stage and the material is not textured. The liquid phase originates from carbon pollution and the c arbon content of the creep sintered specimens is dependant on the trea tment atmosphere.