Effect of grain boundary cracks on the corrosion behaviour of aluminium titanate ceramics in a molten aluminium alloy

The effect of grain boundary cracks on the corrosion behaviour of non-doped aluminium titanate (AT) ceramics was evaluated in a molten Al alloy containing a slight amount of Mg. The corrosion of AT ceramics, in which the AT grains decomposed and subsequently reacted with liquid and/or gaseous Mg to produce MgAl2O4, proceeded not only on sample surfaces in contact and non-contact with the melt, but also on open grain boundary crack surfaces in the ceramic interior. Therefore, the corrosion resistance of AT ceramics can be improved by control of their grain size to close open cracks in the molten alloys.