Effect of mechanical alloying on the microstructural evolution of a ferritic ODS steel with (YeTieAleZr) addition processed by Spark Plasma Sintering (SPS)

Abstract

The high-energy milling is one of the most extended techniques to produce Oxide dispersion

strengthened (ODS) powder steels for nuclear applications. The consequences of the high energy mill

process on the final powders can be measured by means of deformation level, size, morphology and

alloying degree. In this work, an ODS ferritic steel, Fee14Cre5Ale3W-0.4Ti-0.25Y2O3-0.6Zr, was fabricated

using two different mechanical alloying (MA) conditions (Mstd and Mact) and subsequently

consolidated by Spark Plasma Sintering (SPS). Milling conditions were set to evidence the effectivity of

milling by changing the revolutions per minute (rpm) and dwell milling time. Differences on the particle

size distribution as well as on the stored plastic deformation were observed, determining the consolidation

ability of the material and the achieved microstructure. Since recrystallization depends on the

plastic deformation degree, the composition of each particle and the promoted oxide dispersion, a dual

grain size distribution was attained after SPS consolidation. Mact showed the highest areas of ultrafine

regions when the material is consolidated at 1100 C. Microhardness and small punch tests were used to

evaluate the material under room temperature and up to 500 C. The produced materials have attained remarkable mechanical properties under high temperature conditions.