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.
Highlights
Oxide Dispersion Strengthened (ODS) steels have been selected as the most promising candidates for advanced nuclear power plants due to their superior performance over traditional materials at high temperature and their excellent irradiation resistance [1,2,3,4,5,6]
Based on the above analysis, some researchers have investigated the effect of V on the toughness of ODS steel and have found that an appropriate content of V would obviously reduce the ductile-to-brittle transition temperature (DBTT) [15]
Most of the particles presented presented a spherical morphology, and particles in an irregular shape can be seen at the same a spherical morphology, and particles in an irregular shape can be seen at the same time
Summary
ODS steels have been selected as the most promising candidates for advanced nuclear power plants due to their superior performance over traditional materials at high temperature and their excellent irradiation resistance [1,2,3,4,5,6]. V was added to 14Cr ODS steel in order to improve solid solution strength and toughness. Ta is added to 14Cr ODS steel in order to improve mechanical performances. Alloying elements such as Al, Ti, and Zr are generally added to produce a high-density dispersion of (Y, Al, Ti, Zr)-rich oxides [19,20,21,22,23,24,25,26]. Most of the research has been performed on as-heat-treated samples, and information about the characterization of as-consolidated ODS steels has been insufficient. The microstructure and mechanical properties of as-SPSed ODS steel without further heat treatment were investigated in this work. A tensile test of the as-SPSed ODS sample was conducted at room temperature, and the fracture mode was analyzed
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