Microstructure and mechanical properties of Zr₃Al₃C₅-based ceramics synthesized by Al-Si melt infiltration

In this work, bulk Zr₃Al₃C₅-based ceramics were synthesized by the infiltration of Al-Si melt into zirconium carbide (ZrC) perform. The phase composition, microstructure, and mechanical properties of as-fabricated ceramics were studied. The results demonstrate that Si is more effective to reduce the twin boundary energy of ZrC than Al, and thus promotes the decrease of formation temperature of Zr₃Al₃C₅. With the infiltration temperatures increasing from 1200 to 1500 °C, the Zr₃Al₃C₅ content increases from 10 to 49 vol%, which is contributed to the increase of flexural strength from 62±9 to 222±10 MPa, and fracture toughness (K_IC) from 2.8±0.2 to 4.1±0.3 MPa·m^1/2. The decrease of mechanical properties for the samples fabricated at 1600 °C is ascribed to the abnormal growth of Zr₃Al₃C₅ grains.