X. Gu, R.J. Hand is too light, TEM showed up differences between these two phases. High-angle LiAlSOk-LialsO grain boundaries were commonly observed(Fig. 10), which was similar to the high-angle MgAl,Oa MgAL,OA grain boundaries reported by Breval et al. on the Mg-doped system. It was also found that many Fig. 12. TEM micrograph of Al,O, feature showing low- angle Al,O3-AlLO3 grain boundary and high-angle AlO Al grain boundary. Diffraction pattern shows Al,O3 0 1 00 922日KU 2 8 m m Fig 9. SEM micrograph of the surface of a sample fired to 180C for 35 h showing a thin, Li- containing layer on the surface LiAIsON 250nm Fig. 13. TEM micrograph showing Al channel between LiAIsO crystals. Diffraction patterns show Al [0 T 3)(right) and LiAlsos [0 4 3](left) 150nm inclusions of unoxidized al remained within the LiAlsOg matrix(Fig. 11). Low-angle grain bound- fig. 10. TEM m aries were observed between Al2O3 grains(Fig 12 a high-angle LiAl O,O, grain boundary. Diffraction and Al pockets were found set in the Al2O3-Al2O3 pattern shows LiAlsOg [1923] grain boundaries with a high-angle AH-AlO, phase boundary. This was also in agreement with the fea- tures seen in the directed melt oxidation of Al-Mg alloys. .3.7 Some thin channels of aluminium were also found(Fig. 13), which separate neighbouring LiAl Og crystals rather than Al2O, crystals reported in the Mg-doped system by Newkirk et al LiAlsOB Apart from a small amount of surface oxidation of the aluminium blocks, no growth was found in samples containing either 2. 47 or 7-41 wt% Li, CO3 Chat had been healed to 900%C for 3 h, XRD showed however(Fig. 14), that after firing the filler powde 200nm mixture consisted of a-Al2O3, CY-LiAIO2, Y-LiAlO2 and DiAlog. The greater the initial Li,CO,.con Fig. 11. TEM micrograph showing inclusions of Al with tent, the more y-LiAIO, was obtained in the fired mixture932 X. GM, R. J. Hand is too light, TEM showed up differences between these two phases. High-angle LiA&O,-LiAl,O, grain boundaries were commonly observed (Fig. lo), which was similar to the high-angle MgA1,04-MgA&O, grain boundaries reported by Breval et al. on the Mg-doped system. ’ It was also found that many Fig. 12. TEM micrograph of Al,O, feature showing low￾angle Al@-A&O, grain boundary and high-angle AI&Al grain boundary. Diffraction pattern shows A1203 [006]. Fig. 9. SEM micrograph of the surface of a sample tired to I 180°C for 35 h, showing a thin, Li-containing layer on the surface. Fig. 10. TEM micrograph of a LiAl,O, feature showing a high-angle LiAl,Os-LiAI,Os grain boundary. Diffraction pattern shows LiAI,O, [1923]. Fig. 11. TEM micrograph showing inclusions of Al within LiAl,O* matrix. Fig. 13. TEM micrograph showing Al channel between LiAl,O, crystals. Diffraction patterns show Al [0 i 31 (right) and LiAI,O, [0 4 31 (left). inclusions of unoxidized Al remained within the LiAl,Os matrix (Fig. 11). Low-angle grain bound￾aries were observed between A&O, grains (Fig. 12) and Al pockets were found set in the A1,03-A1203 grain boundaries with a high-angle AI-AI,O, phase boundary. This was also in agreement with the fea￾tures seen in the directed melt oxidation of Al-Mg alloys.‘,3,7 Some thin channels of aluminium were also found (Fig. 13), which separate neighbouring LiAl,Os crystals rather than A&O, crystals reported in the Mg-doped system by Newkirk et al.’ Growth into a preform body Apart ‘from a small amount of surface oxidation of the aluminium blocks, no growth was found in samples containing either 2.47 or 7.41 wt% Li,CO, that had been heated to 900°C for 3 h. XRD showed, however (Fig. 14), that after firing the filler powder mixture consisted of a-A&O,, a-LiAlO*, y-LiAIOz and LiA1,08. The greater the initial Li2C03. con￾tent, the more y-LiAlO* was obtained in the fired mixture