Converting titanium–zirconium–molybdenum alloy to oxide-dispersion-strengthened molybdenum alloy via mechanical alloying: A computational study on feasibility and mechanism

Oxygen sensitivity is the key bottleneck for the TZM (Mo—Ti—Zr—C) alloy, limiting both its manufacturability and reliability in extreme service conditions. We present a first-principles computational study investigating the thermodynamic feasibility and atomistic pathways for converting deleterious oxygen into strengthening nano-clusters via mechanical alloying (MA) of TZM with Y2O3 powders. The calculated formation energies, referenced against supersaturated solid solutions, confirm that MA-induced Y—M—O (M=Ti, Zr) precipitation in Mo is energetically favorable. Energy-minimized configurations of multi-atomic Y—M—O clusters reveal a hierarchical precipitation sequence: O—O pair formation → (O,Y)-rich cores → extended Y—M—O nano-clusters. Both Ti and Zr demonstrate strong affinities for the (O,Y) core, preferentially occupying identical crystallographic sites to stabilize the clusters in a comparable manner, while Zr exhibits a modest but systematic energetic advantage over Ti. This nucleation mechanism parallels that in oxide-dispersion-strengthened (ODS) ferritic alloys, but with a substantially greater thermodynamic driving force. This work provides a theoretical basis for the possible role of Y2O3-based MA -technology in controlled oxygen management, where oxygen is trapped in (O,Y)-Ti/Zr precursor clusters and may subsequently contribute to thermally stable strengthening dispersions that enhance high-temperature strength and creep resistance in ODS Mo alloys.