ODS EUROFER Steel Strengthened by Y-(Ce, Hf, La, Sc, and Zr) Complex Oxides

Roman Husák,Hynek Hadraba,Viktor Puchý,Milan Heczko,Tomáš Kruml,Zdeněk Chlup

doi:10.3390/met9111148

Abstract

Oxide dispersion-strengthened (ODS) materials contain homogeneous dispersions of temperature-stable nano-oxides serving as obstacles for dislocations and further pinning of grain boundaries. The strategy for dispersion strengthening based on complex oxides (Y-Hf, -Zr, -Ce, -La) was developed in order to refine oxide dispersion to enhance the dispersion strengthening effect. In this work, the strengthening of EUROFER steel by complex oxides based on Y and elements of the IIIB group (lanthanum, scandium) and IVB group (cerium, hafnium, zirconium) was explored. Interparticle spacing as a dispersoid characteristic appeared to be an important factor in controlling the dispersion strengthening contribution to the yield strength of ODS EUROFER steels. The dispersoid size and average grain size of ODS EUROFER steel were altered in the ranges of 5–13 nm and 0.6–1.7 µm, respectively. Using this strategy, the yield strength of the prepared alloys varied between 550 MPa and 950 MPa depending on the doping element.

Highlights

High chromium-tempered steel EUROFER is variant of reduced activation, ferritic–martensitic (RAFM) steel
The purpose of this work was to investigate the strengthening effects of different complex oxides based on Y and elements of IIIB (La, Sc) and IVB (Ce, Hf, Zr) groups on Oxide dispersion-strengthened (ODS) EUROFER steel
Five different 9Cr EUROFER steels strengthened by Y–Ce, Y–Hf, Y–La, Y–Sc, and investigated

Summary

Introduction

High chromium-tempered steel EUROFER is variant of reduced activation, ferritic–martensitic (RAFM) steel. The development of this class of steel is motivated by its application, which is to serve as a structural material in nuclear fusion reactors. The expected extremely high doses of neutron irradiation led to the choice of ferritic–martensitic steels for their superb high-dose irradiation swelling resistance [1]. Ways to strengthen the material while keeping its low (or reduced) activation have been researched. Strengthening by fine oxide dispersion seems to be a very promising possibility [5]. Yttria oxide was used for its expected high stability during the powder metallurgy route of material preparation. The experiments showed (e.g., [5]) that a small amount (approximately 0.3 wt. %) of a homogeneous dispersion of fine

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Methods

Conclusion