Microstructural and mechanical characterisation of Fe-14Cr-0.22Hf alloy fabricated by spark plasma sintering
journal contributionposted on 05.06.2018 by Maria A. Auger, Yina Huang, Hongtao Zhang, C.A. Jones, Zuliang Hong, M.P. Moody, Steve G. Roberts, Patrick S. Grant
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Fe-14Cr pre-alloyed powder and pure Hf powder were mechanically alloyed to produce powder with nominal composition Fe-14Cr-0.22Hf (wt. %) that was consolidated by the spark plasma sintering (SPS) technique in order to investigate the ability of Hf to produce a nanometric dispersion of oxide particles in a ferritic matrix. Comprehensive microstructural and mechanical characterisation of the as-milled powder and the consolidated material was performed using electron microscopy, X-ray diffraction, atom probe tomography and indentation techniques. It was shown that Hf additions can effectively produce, by internal oxidation, a fine scale dispersion of Hf-O nanoparticles in the consolidated material. A uniform grain structure was produced in the alloy. Although the nanoparticle dispersion was not homogeneous at the finest scale, the resulting dispersion strengthening contributed significantly to the hardness. According to these results, internal oxidation of reactive elements rather than direct addition of oxides may offer additional opportunities in the design and development of oxide dispersion strengthened steels.
The authors acknowledge funding by the UK Engineering and Physical Sciences Research Council (EPSRC) through Grant Numbers EP/H018921/1 and EP/P006566/1 (MAPP), Diamond Light Source for access to beamline I11 (Proposal No. EE10597) and the use of the EPSRC funded National Chemical Database Service hosted by the Royal Society of Chemistry.
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