No ball milling needed: Alternative ODS steel manufacturing with gas atomization reaction synthesis (GARS) and friction-based processing

Abstract

Oxide dispersion strengthened (ODS) steels are promising structural materials for future fusion reactors. The high-density (∼1023/m3) of highly stable Y-(Ti)-O nano-oxides provide high sink strength for radiation resistance and high-temperature (> 650 °C) creep strength. Concomitantly, helium management is enabled by trapping high density (∼1023/m3) of small (< 3 nm) helium bubbles in the vicinity of nano-oxides. However, conventional route of making ODS steels involves prolonged ball milling, canning, degassing, and laborious thermo-mechanical processing (TMP). Such route, especially the batch-by-batch ball milling step, faces persistent challenge with scalability and high costs. Gas atomization reaction synthesis (GARS) method has demonstrated the potential of making precursor ODS steel powders without ball milling, but the nano-oxide density was around 1021/m3 in the final consolidated form by conventional TMP. Taking advantage of GARS precursor powder, we use friction-based processing, including friction consolidation and extrusion, to manufacture ODS steel with further improved nano-oxide characteristics. Preliminary results showed that Y/Ti/O species were intimately mixed and rapidly reacted to form nano-oxides with a number density of ∼1022/m3.