Characterization of 14Cr ODS Steel Fabricated by Spark Plasma Sintering

Abstract

: Oxide Dispersion Strengthened (ODS) steel with a composition of Fe-14Cr-2W-0.2V-0.07Ta-1Al-0.3Y2O3 was fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). All of the investigations were performed on the as-SPSed ODS sample without further heat treatment. The microstructure, particles, and tensile properties of the ODS sample were analyzed. According to the results, both submicron-sized and micron-sized grains existed in the microstructure, showing a bimodal structure. The nanoparticles were homogeneously distributed in the matrix, and the nanoparticles in the ODS sample were mainly Y-Al-O composite oxides. Two kinds of Y-Al-O nanoparticles were identified: Y3Al5O12 particles with body-centered cubic structures and Y4Al2O9 particles with monoclinic structures. The size of the nanoparticles ranged from 2 nm to 61.5 nm, and the average size of the nanoparticles was 11 ± 2.7 nm. Except for the nanoparticles, large M23C6 particles that were detrimental to the ductility of the ODS sample were also identified. These large M23C6 particles possessed a long strip or rod-like morphology, and were generally distributed along the grain boundaries. The generation of cracks generally occurred in the region where the large M23C6 particles were located during the tensile test. The as-SPSed ODS steel possessed a ductile/brittle mixed fracture mode according to the fracture surfaces analysis.