Sintering Behavior of Lanthana-Bearing Nanostructured Ferritic Steel Consolidated via Spark Plasma Sintering

Elemental powder mixture of Fe-14Cr-1Ti-0.3Mo-0.5La2O3 (wt%) composition is mechanically alloyed for different milling durations (5, 10 and 20h) and subsequently consolidated via spark plasma sintering under vacuum at 950°C for 7min. The effects of milling time on the densification behavior and density/microhardness are studied. The sintering activation energy is found to be close to that of grain boundary diffusion. The bimodal grain structure created in the milled and sintered material is found to be a result of milling and not of sintering alone. The oxide particle diameter varies between 2 and 70nm. Faceted precipitates smaller than 10nm in diameter are found to be mostly La-Ti-Cr-enriched complex oxides that restrict further recrystallization and related phenomena.