Heterogeneous nucleation mechanism in TiB reinforced α+β titanium alloy during thermo-mechanical processing

The fundamental understanding of how TiB particles regulate the α-phase heterogeneous nucleation mechanism and texture evolution in TiB reinforced α+β titanium alloys during thermo-mechanical processing remains incomplete, which limits the precise optimization of their microstructure and service performance. To address this issue, TiB reinforced α+β titanium alloys were fabricated via in-situ reaction hot pressing, and hot compression tests were combined with advanced characterization techniques (SEM, EBSD, HRTEM) and molecular dynamics (MD) simulations for systematic investigation. Results demonstrate that TiB particles disperse uniformly in the matrix and act as effective heterogeneous nucleation sites for α grains, which follow a specific crystallographic orientation relationship of {0001} α //{001} TiB and α // TiB , forming low-energy semi-coherent interfaces (minimum 0.89 J/m 2 for the {0001} α //{001} TiB configuration); with increasing compression strain, the α texture gradually weakens and becomes randomized (in contrast to the BOR dominated strong texture in traditional α+β titanium alloys), accompanied by grain refinement and reduced material anisotropy. The underlying mechanism lies in TiB-induced heterogeneous nucleation that disrupts the conventional BOR-governed α texture evolution, driven by the thermodynamically favorable formation of low-energy semi-coherent α-Ti/TiB interfaces. This work provides a comprehensive theoretical basis for optimizing the thermo-mechanical processing parameters of TiB reinforced α+β titanium alloys, facilitating the tailored design of their microstructure and the enhancement of mechanical properties for advanced engineering applications.