Synergistic enhancement of strength and plasticity in Ti–Cu alloys by elimination of pearlite microstructure through Zr alloying

The eutectoid Ti–Cu alloy has the advantages of high strength and hardness. However, the pearlite eutectoid structures with coupled α + Ti₂Cu lamellae result in low plasticity. In this study, a Zr alloying method is proposed to suppress the formation of lamellar pearlite and promote a bainite-like morphology. Increasing the Zr content can transform the α lamellae into rod-like laths and the Ti₂Cu lamellae into dispersed particles, thereby reducing their embrittlement effect. The α laths are further refined to about 0.27 and 0.37 μm with 30% and 50% Zr addition, resulting in strong grain boundary strengthening effects. As a result, the mechanical properties are enhanced after Zr alloying. The best combination of compressive yield strength, maximum strength, and plasticity is achieved with 30% Zr addition, which is about 1040 MPa, 2505 MPa, and 33%, respectively. The results in this study can offer valuable insights into microstructure optimization and performance enhancement in active eutectoid Ti–Cu systems.