Analytical characterization of secondary phases and void distributions in an ultrafine-grained ODS Fe–14Cr model alloy

Abstract

Abstract:Two model Fe-14Cr alloys, one containing 0.3 wt.% of Y 2 O 3 particles, were fabricated by mechanical alloying of Fe and Cr elemental powders under a He atmosphere. They were subsequently consolidated and thermomechanically treated to produce ultra-fine grained materials. Cr-carbides and oxides were found in both alloys. The oxide dispersion-strengthened (ODS) alloy also contained a fine dispersion of nanoparticles, some of them having a Y-O rich core and a Cr-rich shell. Nanometric sized voids were found in both materials, often attached to secondary phases, dislocations and grain boundaries. Their sizes were significantly smaller in the ODS alloy.

Analytical characterisation of oxide dispersion strengthened steels for fusion reactors

“…The voids were smaller than the ones found in the reference non-ODS alloys produced using the same powder metallurgy route but without the nanoparticle dispersion. 18 This supports the role of the nanoparticle/matrix interface as an efficient sink for vacancies and gas atoms, and a preferential site for gas bubble formation, according to recent positron annihilation results obtained in ODS and non-ODS EUROFER steels. 22 The formation of nanovoids appears to be a characteristic of steels processed by mechanical alloying and consolidated by HIP irrespective of the milling conditions and composition, at least if the milling process is carried out in Ar or He.…”

“…22 The formation of nanovoids appears to be a characteristic of steels processed by mechanical alloying and consolidated by HIP irrespective of the milling conditions and composition, at least if the milling process is carried out in Ar or He. 14,18,[23][24][25] Some of these voids can contain entrapped gas atoms coming from the milling atmosphere. Void coarsening and gas bubble formation by gas diffusion towards the voids have been reported for ODS and non-ODS EUROFER steels subjected to isochronal annealing.…”

Tensile and fracture characteristics of oxide dispersion strengthened Fe–12Cr produced by hot isostatic pressing

“…Forging before the heat treat-ment does not significantly change the microhardness, at least for the heat treated non-ODS Fe12Cr alloy, as the microhardness value is similar to the one found in a non-ODS Fe14Cr alloy forged at 1323 K and subsequently heat treated at 1123 K. When comparing the ODS counterparts, the microhardness value is $ 8% lower in the ODS Fe12Cr than in the forged -heat treated ODS Fe14Cr alloy containing 0.3 wt%Y 2 O 3 particles [12]. The higher homogeneity of the nanoparticle dispersion found in this ODS Fe14Cr alloy would account for the difference in hardness [10,13]. Fig.…”

Mechanical Characterization of a Nano-ODS Steel Prepared by Low-Energy Mechanical Alloying

“…A further contribution to enhance high-temperature performances can also be obtained through grain refinement. An optimal solution is the combination of the effects of oxide dispersion strengthening and ultra-fine grains [6,7]. Furthermore, oxide nanoparticles in the steel matrix act as sinks for point defects thus improve the resistance Metals 2017, 7, 283; doi:10.3390/met7080283…”