Aluminum Oxide‐Titanium Oxide Solid Solution

An oxide of titanium, apparently Ti 2 O 3 , showed solid solubility in Al 2 O 3 of 1.0, 1.8, and 2.5 mole % at 1400°, 1600°, and 1700°C, respectively, when heated in hydrogen with a dew point of about ‐50°C. At the same temperatures in air, however, no indication of solid solubility (of TiO 2 , presumably) was found by X‐ray diffraction. It is concluded, therefore, that titania effects densification and grain growth of alumina by grain‐boundary action rather than by a defect mechanism in the corundum lattice resulting from the substitutional solution of Ti 4+ ions.