In the Al
2O
3-TiO
2 system, solid solutions of AIO(OH) gel are formed between 5 and 20 mol% TiO
2 by the simultaneous hydrolysis of aluminium and titanium alkoxides, followed by washing and drying. After dehydration γ-Al
2O
3 solid solutions crystallize slowly from amorphous materials. At higher temperatures, rutile (TiO
2) is formed directly with the transformation of γ-Al
2O
3 phases into corundum. Corundum-rutile composite ceramics with dispersed fine pores generated from the decomposition of Al
2TiO
5 have been fabricated as follows:(1) hot pressing for 2 h at 1350°C under 35 MPa using γ-Al
2O
3 solid solutions, (2) heating for 1 h at 1500°C to achieve the complete formation of Al
2TiO
5, and (3) annealing for 7 h at 1000°C to decompose of Al
2TiO
5 into corundum and rutile. Their mechanical properties have been examined. The bending strength yields the maximum value of 365 MPa with 15 mol% TiO
2 content whereas the fracture toughness increases from 4.7 to 6.2 MPam
1/2 with increasing TiO
2 content.
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