Phase interface engineering: A new route towards ultrastrong yet ductile Mo alloy

Oxide dispersion strengthened (ODS) refractory metals, represented by tungsten and molybdenum alloy, possesses many excellent properties such as high-temperature strength, outstanding thermal microstructure stability and good resistances to oxidation and corrosion. However, in traditional preparation technologies, these ex-situ oxides usually form poor oxide/matrix interface relationships and keep coarse sizes at grain boundaries (GBs), which prominently limit the improvement of alloy mechanical properties until now. In this work, we skillfully employed novel phase interface engineering to successfully construct completely coherent oxide/matrix interfaces in ODS Mo alloys through the newly formed ternary phase oxide nanoparticles or diffusion layers. Furthermore, these ODS Mo alloys are characterized by ultrafine grains, ultrafine subgrains, small and dispersed intragranular and intergranular particles. An amount of oxygen impurities can also be depleted via phase interface engineering, thus purifying Mo matrix. The phase interface engineering endows ODS Mo alloys with ultrahigh strength, excellent ductility and excellent hot machinability, which illuminates a new research direction for those ex-situ oxide dispersion strengthened alloys with excellent mechanical properties.