Tailoring a Dual‐Scale Heterostructure With γ ‐Textures and Nano‐ β ₀ Dispersion for Synergistic Enhancement of Mechanical Pr

ABSTRACT

The limited crack resistance of coarse grain boundaries and coarse interfaces leads to an incompatibility between high‐temperature strength and ductility in TiAl alloys. Tailoring stress‐oriented textures and multiscale heterogeneous interfaces can effectively impede crack propagation, thereby overcoming this trade‐off. In this study, a novel dual‐scale three‐phase heterogeneous microstructure was developed through thermomechanical processing, enabling synergistic regulation of texture and interface characteristics. The resulting microstructure is composed of micrometer‐scale equiaxed γ phase, equiaxed α ₂ phase, and nanoscale equiaxed β ₀ phase. At room temperature, this microstructure exhibits higher fracture toughness and better crack resistance than the coarse lamellar colony microstructure. At 900°C, tensile strength comparable to that of the initial lamellar is retained, whereas elongation is increased by a factor of five. The retained strength is attributed to the combined effects of texture strengthening from equiaxed γ phases and dispersion strengthening from nano‐ β ₀ precipitates. The enhanced plasticity arises from the activation of multiple slip systems within the γ textures and stress dissipation at the nano‐ γ / β ₀ interfaces. This study establishes a microstructural design strategy that simultaneously exploits texture, phase distribution, and nano‐precipitation, providing a viable pathway for the design of TiAl alloys with superior mechanical properties under high‐temperature service conditions.