Correlation between Grain Size and Thermal Expansion for Aluminum Titanate Materials

Al2TiO5 materials were sintered under different conditions to produce different grain sizes. The resultant microcracked materials exhibited a range of bulk thermal expansions which showed a strong correlation with average grain size. An Al2TiO5 average grain size of 3 to 4 μm was the minimum at which the size and population of microcracks effectively reduced the apparent thermal expansion of the polycrystalline material. Further increases in grain size resulted in a rapid drop in the bulk thermal expansion, followed by diminishing decreases with further increases in grain size. Small amounts of phase stabilizers (