Processing and crystallisation of rapidly solidified Al2O3–Y2O3fibres

Amorphous fibres of the Al2O3–Y2O3system were prepared by a melt extraction technique, and subjected to crystallisation. The quality of the melt extracted fibres is controlled by the wheel edge and rotational speed, with both having a significant effect on fibre diameter and avoidance of irregularities and instabilities along the fibre length. Tensile strength in the glassy state varied from 0·6 to 1·0 GPa. Crystallisation activation energies calculated from scan-rate dependence of DTA peaks are 741 and 1374 kJ mol-1for E1 (Al2O3–yttrium aluminium garnet (YAG) eutectic), 390 kJ mol-1for YAG, and 438 kJ mol-1for E2 (YAG–yttrium aluminium perovskite (YAP) eutectic) by the Kissinger method; and 698 and 1346 kJ mol-1for E1, 352 kJ mol-1for YAG, and 399 kJ mol-1for E2 by the Augis–Bennett method.