Effect of Interface Wetting Agents on Impact Toughness and Bending Properties of ZrO₂-Toughened Al₂O₃ Particle-Reinforced High Chromium Cast Iron Matrix Composite

The effects of Fe (100% Fe), Ti15 (85% Fe, 15% Ti), and Cr60 (40% Fe, 60% Cr) on the impact toughness and bending properties of ZrO₂-toughened Al₂O₃ particles (ZTA_P)-reinforced high chromium cast iron (HCCI) composites were investigated in this study, and the fracture mechanisms were analyzed. Fe, Ti15, and Cr60 enhanced wettability and interface bonding. Fe-coated composites exhibited the highest impact toughness (2.1 J/cm²), while Cr60-coated composites had the lowest (1.3 J/cm²), with Ti15 intermediate (1.6 J/cm²). Fe-coated ZTA_P composites also had the highest flexural strength (219.6 MPa) and modulus (32.2 GPa). Ti15-coated ZTA_P showed slightly better flexural properties than Cr60-coated ZTA_P, with higher strength (160 MPa vs. 150.7 MPa) and modulus (29.0 GPa vs. 28.1 GPa). Ti15-coated ZTA_P composites formed brittle carbides at the interface, while Cr60-coated ZTA_P composites developed glassy phases, which promoted crack propagation and ZTA_P pullout, thereby reducing impact toughness and bending properties. In contrast, Fe-coated composites formed toughness-enhancing MnAl₆, which improved both impact toughness and bending properties by absorbing impact energy and preventing ZTA_P pullout.