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Title: Evidence for core–shell nanoclusters in oxygen dispersion strengthened steels measured using X-ray absorption spectroscopy

Nanostructured ferritic alloys (NFA) dispersion strengthened by an ultra high density of Y–Ti–O enriched nano-features (NF) exhibit superior creep strength and the potential for high resistance to radiation damage. However, the detailed character of the NF, that precipitate from solid solution during hot consolidation of metallic powders mechanically alloyed with Y₂O₃, are not well understood. In order to clarify the nature of the NF, X-ray absorption spectroscopy (XAS) technique, including X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) were used to characterize the local structure of the Ti and Y atoms in both NFA powders and consolidated alloys. The powders were characterized in the as-received, as-milled and after annealing milled powders at 850, 1000 and 1150 °C. The consolidated alloys included powders hot isostatic pressed (HIPed) at 1150 °C and commercial vendor alloys, MA957 and J12YWT. The NFA XAS data were compared various Ti and Y-oxide standards. The XANES and EXAFS spectra for the annealed and HIPed powders are similar and show high temperature heat treatments shift the Y and Ti to more oxidized states that are consistent with combinations of Y₂Ti₂O₇ and, especially, TiO. However, the MA957 and J12YWT and annealed–consolidated powder data differ.more » The commercial vendor alloys results more closely resemble the as-milled powder data and all show that a significant fraction of substitutional Ti remains dissolved in the (BCC) ferrite matrix.« less
Authors:
; ;  [1]
  1. UCSB
Publication Date:
OSTI Identifier:
1107435
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Nucl. Mater.; Journal Volume: 445; Journal Issue: (1-3) ; 02, 2014
Research Org:
Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
Sponsoring Org:
DOE - BASIC ENERGY SCIENCES
Country of Publication:
United States
Language:
ENGLISH
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS