In situ fabrication of spherical oxide dispersion strengthened Ti powder through gas atomization

Abstract

Oxide dispersion strengthened (ODS) alloys exhibit excellent mechanical properties due to fine oxide dispersion, but they have great limitations due to utilizing powder fabrication via mechanical alloying. Therefore, this study examined the alloy composition and process that can fabricate ODS titanium (Ti) powder in situ through a gas atomization method. The composition and content of the oxide, which can dissolve in molten Ti during melting and precipitate inside powders during cooling in the gas atomization, were derived through thermodynamic calculations. The ODS Ti alloy composition of Ti + 1 wt% yttria (Y2O3) was derived, and the alloy was prepared as a powder through an electrode induction melting gas atomization (EIGA) method. First, rod-shaped ingots were prepared through vacuum arc remelting (VAR), and Y2O3 was coarsely precipitated along the grain boundaries due to the slow cooling rate. Then, the ODS Ti powder was fabricated by EIGA using the rod ingot and spherical powders could be continuously fabricated. The cross-section microstructure of the powder was observed, and the Y2O3 particles with several tens of nm were uniformly distributed inside the powder. These thermodynamic calculations and experiments confirmed that ODS Ti powder could be fabricated in situ using the gas atomization method.