Ceramic-Reinforced γ-TiAl-Based Composites: Synthesis, Structure, and Properties.

Prior research has explored γ-TiAl alloys for their low density and high-temperature performance, but their mechanical limitations remain a challenge. Existing studies have focused on alloying strategies and microstructural control to enhance properties. However, the integration of ceramic reinforcement in layered structures has not been fully characterized. This gap motivated the investigation of multilayer composites to improve strength and creep resistance. No prior work had resolved how ceramic layers affect mechanical behavior under different loading directions. The role of MAX phases in such systems is also not well understood. This study addresses how interfacial reactions and microstructural evolution influence composite performance. The goal is to establish a foundation for optimizing layered TiAl-based materials. These findings may contribute to the development of lightweight, high-strength structural components.

The aim of this research was to synthesize and evaluate new TiAl-based composites reinforced with ceramic layers. The specific problem addressed is the mechanical limitations of γ-TiAl alloys under load. The motivation stems from the need for materials with improved strength and creep resistance for high-temperature applications. The study focused on understanding how layered structures affect mechanical properties. The researchers sought to determine the role of ceramic reinforcement in microhardness and compressive strength. They also aimed to identify the formation of intermediate phases during sintering. The study examined how loading direction influences creep behavior. The ultimate goal was to establish a correlation between microstructure and mechanical performance.

The materials were fabricated using spark plasma sintering of Ti and Al foils with TiB₂ and TiC particles. The sintering process occurred at 1250 °C under controlled conditions. In situ synchrotron X-ray diffraction tracked phase formation during heating. Transmission electron microscopy and scanning electron microscopy analyzed microstructural details. Energy dispersive X-ray spectroscopy identified elemental composition at interfaces. The researchers evaluated the formation of α₂ + γ structures and MAX phases. Mechanical properties were tested using microhardness, compression, and creep measurements. The orientation of layers relative to loading direction was a key variable in the experiments.

The composites exhibited a layered structure of α₂-TiAl, γ-TiAl, and ceramic reinforcement. In situ XRD confirmed the formation of α₂ + γ structures through solid-liquid and solid-solid reactions. The TiC particles reacted with Ti and Al to form a Ti₂AlC MAX phase. No chemical interaction was observed between TiB₂ and the matrix. Microhardness values correlated with the hardness of reinforcing components. Compressive strength was higher when loading was perpendicular to the layers. Creep resistance was better when loading was parallel to the layers. These results suggest that layer orientation significantly affects mechanical performance.

The study demonstrated that ceramic-reinforced TiAl composites can be synthesized with controlled microstructures. The formation of α₂ + γ structures and MAX phases was confirmed through multiple analytical techniques. The orientation of layers influenced compressive strength and creep resistance. The absence of TiB₂-matrix reactions suggests compatibility in the sintering process. Microhardness values reflect the contribution of reinforcing components. The researchers propose that layered structures can be tailored for specific mechanical needs. These findings support the potential of such composites for high-temperature applications. The study provides a basis for further optimization of layered TiAl-based materials.