Insight of the microstructure evolution and performance enhancement of spinodal decomposition in (Ti, Zr)C composite carbide ceramics: Multiscale simulation and experimental investigation

Abstract

Traditional carbide ceramics face a sharp trade-off between hardness and toughness, leading to a significantly reduced lifespan under harsh service conditions like wear, impact, corrosion, and high temperatures. The spinodal decomposition leads to the formation of nano-lamellar structures, serving to refine grain sizes, thus paving the way to simultaneously improve the hardness and toughness of composite carbide ceramics. A wide range of composite carbides can be prepared, but their complex microstructure evolution during aging makes performance optimization extremely challenging. In this work, a strategy by combining the multiscale simulations and experiments is proposed to systematically study the influence of the composition and process on the spinodal decomposition structure and performance. Taking (Ti, Zr)C carbide ceramics as a representative example, three distinct compositions of (Ti, Zr)C solid solutions were successfully synthesized via a sol-gel combined with spark plasma sintering method at 1800 °C, guided by thermodynamic calculations. The influence of aging temperature and duration on spinodal decomposition microstructure evolution in (Ti, Zr)C carbide ceramics was studied by integrating phase-field simulations and first-principles calculations with key experimental observations. After spinodal decomposition, numerous nanoscale nodular structures form, accompanied by the generation of dislocations, leading to a significant improvement in both hardness and toughness of the composite carbides. After aging at 1300 °C for 3 h, the composite carbides achieved peak hardness at 2436 HV, accompanied by a fracture toughness of 3.24 MPa·m^1/2. This research provides a scientific approach to improving the hardness and toughness of carbide ceramics through spinodal decomposition, offering essential theoretical foundations for microstructural control and synergistic optimization of performance in innovative carbide ceramics.