Abstract: Enhancing the strength of Mo-based alloys by adding oxide dispersion phase often comes at the expense of ductility, primarily due to the pronounced grain-boundary segregation tendency and incoherent interfaces of added oxides. In this study, we report a Mo-CeO₂ alloy with unparalleled ductility, prepared by co-deposited chemistry method, low-temperature sintering, and rotary swaging. The resulting microstructure exhibits a synergistic oxide distribution both within Mo grains (number fraction of 82%) and at grain boundaries. More critically, the intragranular CeO₂, with an average size of 36 nm, demonstrates a CeO₂(200)//Mo(101) semi-coherent interface with the Mo matrix. This configuration not only harnesses the strengthening and strain hardening effects typical of conventional oxide dispersion phases but also further improves the ductility through interface stress relaxation. Additionally, this alloy develops a <111>//rolling direction soft orientation texture after annealing, which is also crucial for improving ductility by promoting the formation and orderly motion of dislocations. The uniformly dispersed CeO₂ particles play a crucial role in stabilizing grain microstructure, effectively suppressing recrystallization even after annealing at 1520 °C. Grain boundary strengthening and second-phase strengthening are the predominant strengthening mechanisms for the fabricated alloy. Consequently, the Mo-CeO₂ alloy we developed attains enhanced strength (σ_u∼682 MPa) along with a ductility (e_f∼59%) that is nearly double that of pure Mo. Our research underscores the importance of oxide-induced microstructural control in overcoming the strength-ductility trade-off and establishes a viable pathway for fabricating high-performance oxide dispersion-strengthened refractory metals.

Key words: ODS Mo, CeO₂, Oxide distribution, Interfacial structure, Strengthening and ductilization