Incidence of mechanical alloying contamination on oxides and carbides formation in ODS ferritic steels

Olier, P.; Couvrat, Mathieu; Cayron, Cyril; Lochet, N.; Chaffron, L.

doi:10.1016/j.jnucmat.2013.03.090

Cited by 27 publications

(20 citation statements)

References 20 publications

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“…The introduction of impurities could not be completely avoided even when all of the handling of powders before mechanical alloying and the milling process were under an argon atmosphere. It has been proven that a longer milling time increases the contamination of impurities [20,36,37], which is ascribed to the wearing of milling balls. Deformation and fracture of powder grains can occur because of the high energy of milling.…”

Section: Nanoparticlesmentioning

confidence: 99%

“…This phenomenon is consequently detrimental to the purity of the as-milled powders. According to some investigations, reducing the mechanical alloying time and improving the purity of the argon atmosphere are effective ways to reduce carbon contamination [27][28][29]36]. The existence of M 23 C 6 particles could not effectively hinder dislocation motion and grain boundary movement because of their large size, and their presence concurrently decreased ductility.…”

Section: Nanoparticlesmentioning

confidence: 99%

“…The effect of densification was indeed one of the factors that could cause the formation of pores, though was not the major one. The entrapment of argon during mechanical milling leads to the formation of pores, and large M 23 C 6 particles result from the contamination of the as-milled powders [36]. The existence of a large amount of brittle M 23 C 6 particles was extremely detrimental to the ductility of the tensile sample.…”

Section: Tensile Propertiesmentioning

confidence: 99%

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Characterization of 14Cr ODS Steel Fabricated by Spark Plasma Sintering

Zhao

Qiao

Liu

et al. 2019

Metals

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: 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.

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Section: Nanoparticlesmentioning

confidence: 99%

Section: Nanoparticlesmentioning

confidence: 99%

Section: Tensile Propertiesmentioning

confidence: 99%

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Characterization of 14Cr ODS Steel Fabricated by Spark Plasma Sintering

Zhao

Qiao

Liu

et al. 2019

Metals

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“…Some researchers suggest that segregation of C can also promote the generation of martensite [18]. The contamination of C is inevitable both in the pre-alloyed powders and during the mechanical milling or alloying process [31][32][33]. All the SPSed steels undergo the same powder metallurgy process, so the amount of C contamination should be same in all cases.…”

Section: Spsed Microstructurementioning

confidence: 99%

Inhibition Effect of Ti on the Formation of Martensite Lath in 14Cr Oxide Dispersion Strengthened Steel

Zhao

et al. 2018

Metals

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Three model powders defined as MP powders (milled pre-alloyed powders), mixed powders (MX, 50 wt.% MP powders + 50 wt.% Oxide-Dispersion Strengthened powders) and Oxide Dispersion Strengthened (ODS) powders (alloyed pre-alloyed powders with the addition of Ti and Y2O3) are obtained under identical ball milling parameters. These powders are then consolidated under same sintering condition by spark plasma sintering (SPS) in order to investigate the formation mechanism of martensite lath in the MP steel and the effect of Ti on the stability of ferrite. The results indicate that the addition of Y2O3 and Ti powders can act as friction material during the mechanical alloying process, thus promoting the refinement effect. The formation of martensite lath in the MP steel is attributed to the local Cr depletion resulted from the large amounts of M23C6 precipitation. Ti possesses a strong affinity to C and long range diffusion ability, which efficiently prevents the martensite lath formation and local Cr depletion. Present study supports the conclusion that the lack of martensite in the MX and ODS steel is due to the addition of Ti. Secondary phases in these steels are identified and analyzed as well.

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“…Indeed, the milling time and mill type are source of light element (C or O) contaminations. Olier et al [23] observed titanium carbides of~200 nm after consolidation in an ODS milled in an attritor while such precipitates have not been observed with the same milling conditions in a ball mill. They concluded that attrition is a high carbon contamination process.…”

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confidence: 99%