Phase Transformations in Dicalcium Silicate: III, Effects of Barium on the Stability of Fine‐Grained α′_L and β Phases

Fine‐grained materials containing both α′‐Ca₂SiO₄ and β‐Ca₂SiO₄ were fabricated as an analogue to tetragonal zir‐conia polycrystals (TZP) with the use of barium to stabilize the high‐temperature polymorphs of Ca₂SiO₄. The micro‐structure of dense α′_L‐Ca₂SiO₄ exhibited none of the twinning or residual strain previously observed in fine‐grained β‐Ca₂SiO₄ and there was no evidence of barium‐rich grain boundary phases. Materials fired in the α region exhibited large grain sizes. Stress‐induced α′_L→β transformation was observed on ground surfaces but not on fracture surfaces.