Microstructural design and property optimization of mo alloys with high performance

The high-temperature stability and mechanical properties of refractory molybdenum alloys are highly desirable for a wide range of critical applications. But molybdenum (Mo) alloys are also a well-known example of body-centered-cubic materials that suffer from low ductility and limited formability. In this paper, we firstly discuss the microstructure-property relationships in traditional oxide dispersion-strengthened Mo alloys and analyze the fracture mechanisms. Based on these understandings, we propose a new nanostructuring strategy to solve the long-standing low-ductility problem by optimizing the distribution of the grains, strengthening dispersions and solutes. In particular, a simple and cost-effective molecular-level liquid-liquid mixing/doping technique is developed to achieve ultrafine submicron-sized grains with nanosized oxide particles uniformly distributed in the grain interior. The resulting nanostructured Mo alloys boast not only a high yield strength of over 800 MPa but at the same time an extraordinary tensile elongation as large as ~40% at room temperature, which is increased by about 15% and above 160%, respectively, when compared with the ODS Mo alloys prepared by conventional methods. The new processing route can be readily adapted for large-scale industrial productions of ductile Moalloys that can be extensively processed and shaped, including deep drawing, at low temperatures. Our findings represent a pathway towards engineering dispersion-strengthened materials with simultaneously high strength and ductility, a combination beyond conventional trends and expectations, which should be applicable to refractory metals such as tungsten.