Microstructure and mechanical properties of titanium matrix composites with alternating layers α '/β formed by selective laser melting

Mo 2 C/Ti6Al4V composites were fabricated via selective laser melting (SLM) with varying Mo 2 C conditions, and the microstructure evolution and mechanical properties were systematically examined. The results reveal that most Mo 2 C particles undergo in-situ reactions with the titanium matrix during SLM processing, resulting in the formation of nanoscale whisker-like TiC. The segregation of Mo promotes β -Ti phase formation, yielding a characteristic microstructure where α′-Ti domains in Mo-poor regions alternate with β -Ti bands in Mo-rich zones. Furthermore, increasing Mo 2 C content facilitates the refinement of both α′ -Ti and primary β -Ti columnar grains. Compared with Ti6Al4V, the titanium matrix composites exhibited 27.2% and 34.3% enhancements in tensile strength and microhardness, respectively. To maintain optimal strength-ductility balance, the optimal Mo 2 C addition should not exceed 2 wt%. The improved mechanical performance is attributed to the synergistic effects of grain refinement strengthening and dispersion strengthening mechanisms, arising from the unique combination of α′ / β microstructures, nano-scale TiC precipitates, and residual Mo 2 C. These findings provide critical guidance for selecting reinforcement materials in additive manufacturing to develop high-performance composite systems.