The role of borides in near-gamma titanium aluminides

This paper reviews how boride additions affect the microstructure, strength and creep properties of alpha (2) + gamma titanium aluminides. Important t itanium boride structures in near-gamma alloys include TiB2 and TiB; their structures and stability ranges are discussed first. Then, influences on ma trix microstructure-grain refinement, enhanced microstructural conversion k inetics, and the stabilization of fine lamellar structure-are elaborated up on, for matrix microstructure plays the most important role in determining mechanical properties. The combined effects of reinforcement and microstruc ture on mechanical behavior are then explored, illustrating how the incorpo ration of grain refiners, such as titanium borides, facilitates thermomecha nical processing and enables the tailoring of microstructure to optimize sp ecific mechanical properties.