Abstract

Fe-10Cr-5Y2O3 powders were mechanically alloyed using a high energy horizontal ball-mill apparatus, and the effect of heat treatment on the behavior of nano-sized oxide particles formed in the mechanically alloyed Fe-10Cr-5Y2O3 powders was investigated. Elongated Cr-rich and Y-rich oxides were observed in the mechanically alloyed powders. During the heating of these powders above 700 °C, the elongated Cr-rich oxides were dramatically changed to a near- spherical morphology. Cubic-Y2O3, monoclinic-Y2O3 and YFeO3 phases were also found after heat treatment at 1150 °C for 1h, indicating that the Y-rich oxide phase was transformed to the cubic-Y2O3, monoclinic-Y2O3 and YFeO3 ones. It is thus concluded that both a morphological change of Cr-rich oxide and a phase transformation of Y-rich oxide during the heating of mechanically alloyed powders could be mainly attributed to extremely high energy, accumulated by the mechanical alloying process.

Highlights

  • Oxide dispersion strengthened (ODS) steels have an excellent irradiation resistance and superior high-temperature mechanical properties [1,2]

  • In order to enhance the performance of ODS steels, the oxide particles should be a few nanometers in size and need to be homogeneously distributed in the matrix

  • The mechanically alloyed Fe-10Cr-5Y2 O3 powders showed the typical features of severe plastic deformation, which was ascribed to the repeated fracture and cold-welding of the powder mixture

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Summary

Introduction

Oxide dispersion strengthened (ODS) steels have an excellent irradiation resistance and superior high-temperature mechanical properties [1,2]. The improved irradiation resistance and mechanical properties of ODS steels come from the presence of nano-sized oxide precipitates in the matrix [3]. A 10 wt.% Cr ODS ferritic/martensitic steel with some minor elements has been newly developed for the in-core structural components of SFR, which has very attractive microstructures to achieve both superior creep and radiation resistances at high temperatures [1,4]. The characteristics of ODS steels are mainly decided by the size, inter-spacing and the crystallographic relationship with the matrix of oxide particles [6]. In order to enhance the performance of ODS steels, the oxide particles should be a few nanometers in size and need to be homogeneously distributed in the matrix

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