Enhancing strength and ductility in Ti64 Alloys: Optimizing dual-phase heterostructures and TRIP effects via high-entropy alloy content modulation

• Introduced an innovative in-situ multi-alloying strategy combining Ti64 with high-entropy alloy (HEA) CoCrFeNiMn. • Achieved a 37.5% increase in ultimate tensile strength and 140% improvement in elongation compared to conventional Ti64. • Developed a bimodal microstructure of ultrafine α′ martensite and metastable β phase. • Demonstrated progressive TRIP effect for improved work hardening. The mechanical performance of Ti-6Al-4 V (Ti64) alloys fabricated via Laser Powder Bed Fusion (L-PBF) can be significantly influenced by the addition of high-entropy alloy (HEA) particles. This study investigates the impact of varying HEA content on the microstructure and mechanical properties of Ti64 alloys. By systematically optimizing the HEA content, a lamellar dual-phase microstructure is achieved. The interplay between the refined α’ martensitic phase and the metastable β phase promotes a progressive transformation-induced plasticity (TRIP) effect, enabling superior strain hardening and stress redistribution. The Ti64-(3.0 wt%) HEA alloy achieves an ultimate tensile strength of 1438.1 MPa and elongation of 9.0 %, representing an optimal balance of strength and ductility.