Investigation of Grain Boundary Precipitation in Titanium Alloys using 3D Experimental Characterization and Computational Simulation

Titanium alloys predominantly derive their high strength from the interfaces between the second-phase alpha precipitates and the beta matrix that serve as the barrier for the dislocation motion. Thus, understanding, prediction and control of the size, morphology and spatial distribution including that of its orientation variants of alpha precipitates are highly desirable for engineering desired microstructures for optimal properties targeting specific applications. Our previous study in a Ti-5Al-5Mo-5V-3Cr (wt%, Ti-5553) alloy has shown that fine-scale alpha precipitates without micro-texture can nucleate from the pre-formed omega/beta interface that leads to ultra-high strength but relatively low ductility. In this work, the grain boundary alpha precipitates in the Ti-5553 alloy were investigated using the 3D focused ion beam/scanning electron microscopy (FIB/SEM) tomography and 3D phase field simulations. The 3D morphology of grain boundary alpha precipitates was characterized by the FIB serial sectioning using Thermo Scientific Scios 2 FIB/SEM and reconstructed using the MIPAP image analysis software. The nucleation and growth of grain boundary alpha precipitates was simulated using 3D phase field simulation. The influence of the inclination angle between the habit plane of the selected variant for grain boundary alpha and the hosting grain boundary plane in determining the morphology of grain boundary precipitates in titanium alloys will be introduced. This work is supported by the National Science Foundation, grant CMMI-2122272.