The origin of exceptionally large ductility in Molybdenum Alloys dispersed with Irregular-Shaped La2O3 Nano-Particles

Abstract

Abstract Molybdenum and its alloys typically exhibit superior strength compared with other body centered cubic materials, while the pronounced decrease in ductility at lower temperatures often imped their widespread applications. In this study, we demonstrate the attainment of extraordinary ductility by utilizing rotary-swaging to process a Mo alloy containing rare earth La2O3 nanoparticles —a rarity within the domain of Mo-based materials. Our atomic structure analysis elucidates that the exceptionally large ductility is originated from the substantial variations in electronic density of states, a characteristic intrinsic to rare-earth elements, which can expedite the generation of oxygen vacancies. This, in turn, facilitates the amorphization of the oxide-matrix interface under precise processing control, which then exhibits a propensity for vacancy absorption and modification of dislocation configurations. Furthermore, by imparting irregular shapes to the La2O3 nanoparticles through rotary-swaging, we succeeded in engendering multiple dislocation sources in the vicinity of the interface as incoming dislocations interact with these La2O3 nanoparticles. The newly generated dislocation sources persistently operate as potent dislocation initiators under applied stress even at reduced temperatures, resulting in the formation of diverse dislocation types and intricate dislocation networks and ultimately leading to superior dislocation plasticity.