Hot forging characteristics of transformation-toughened Al₂O₃/ZrO₂ composites

Fine grain, transformation-toughened Al₂O₃/ZrO₂ (tetragonal, 5–30 vol. %) composites can exhibit both large deformation strains (80%) and strain rates (> 0.001 s⁻¹) without tearing, cavitating, or cracking during hot forging at 1500 °C. Deformability increases with ZrO₂ content. The Al₂O₃ grains grow, develop a crystallographic orientation, and form column structures with increasing deformation. The deformation behavior of the composite series primarily depends on the content of the ZrO₂ phase. In this regard, two deformation regimes were observed that appear to be separated by the volume fraction where the ZrO₂ phase might form a connective network.