Synthesis and characterization of high chromium zirconiaoxide dispersion strengthened (ODS) steel

Abstract

High Chromium ODS ferritic steel dispersed by zirconia was synthesized by the Mechanical Alloying process for application as high-temperature nuclear reactor structure material. The zirconia was chosen as dispersoid to increase the oxidation resistance of the steel. The powders of Fe and Cr with composition of Fe-25 wt.% Cr and 0.5 wt.% Zr2O3 were processed by milling and isostatic compaction then continued with the sintering process for consolidation. The process of sintering was performed by the plasma-based heating using the new apparatus of APS (Arc Plasma Sintering). The sintering was processed with 40 A current and 22 minutes sintering time to result in the optimal Fe-Cr alloy formation. A microscopy technique with scanning electron microscopy (SEM), and X-ray diffraction (XRD) were applied to analyze the mechanism of the alloying process. The Vickers hardness measurement and the oxidation test were carried out to evaluate the mechanical and high-temperature oxidation behavior. The alloying process was considered by the Fe-Cr interdiffusion with Cr the faster one. The distribution of zirconia observed by SEM-mapping showed the homogeneity distribution in the matrix of the alloy. The Vicker hardness of 142.8 VHN was believed caused by the oxide strengthen and fining the grain. The parabolic oxidation curve obtains from the MSB oxidation test showed good oxidation resistance caused by the formation of the protective layer of Fe2O3 and some metastable of ZrO.