Strengthening in TiB-Reinforced Dual-phase Titanium Matrix Composites: Effect of TiB Volume Fraction and Matrix Microstructure

The influence of matrix microstructure on the strengthening behavior of titanium matrix composites (TMCs) has been rarely explored, and existing strengthening models often overlook the complexity introduced by dual-phase microstructural evolution. In this study, a series of TiB-reinforced dual-phase TMCs containing 0 to 8 vol pct TiB were fabricated via powder metallurgy (PM) and then heat treated following different protocols, resulting in equiaxed, lamellar, bimodal, and basketweave matrix microstructures. The effects of TiB content and matrix microstructure on mechanical properties and strengthening mechanisms were systematically examined through uniaxial compression and hardness tests. A schematic continuous cooling transformation diagram was constructed to correlate phase evolution with processing conditions. Quantitative analysis of the strengthening mechanisms reveal that load transfer is the dominant contributor. When the matrix morphology and hardness remain invariant, a constant strengthening efficiency of ~ 40 MPa per vol pct TiB was observed. However, variations in the proportion of hard phases (e.g., β_tf and α′) in matrix significantly affect the strengthening efficiency. These findings highlight the pivotal role of matrix microstructure in governing the mechanical behavior of dual-phase TMCs and provide insights for more accurate modeling and design of advanced composites.