• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.580-581
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• 2006

The present paper investigates the possibilities of niobium using for the mechanical properties of the common low alloyed Cu-Ni-Mo-C sintered structural steels enhancing. On both thermodynamic and experimental bases there were demonstrated the Nb nitrides/carbides/carbonitrides preferential formation in these steels during sintering in dissociated ammonia at both common and elevated temperatures. The obtained results for $0.2\;{\div}\;1.0\;%$ fine Nb powder and 0.3% graphite additions to Distaloy AB iron base powder cold compacted and sintered in dissociated ammonia proved the expected strengthening effect, leading to higher mechanical properties of the processed steels than of the common Cu-Ni-Mo-C ones.

• Journal of Powder Materials
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• v.24 no.2
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• pp.133-140
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• 2017

This study investigates the oxidation properties of Fe-14Cr ferritic oxide-dispersion-strengthened (ODS) steel at various high temperatures (900, 1000, and $1100^{\circ}C$ for 24 h). The initial microstructure shows that no clear structural change occurs even under high-temperature heat treatment, and the average measured grain size is 0.4 and $1.1{\mu}m$ for the as-fabricated and heat-treated specimens, respectively. Y-Ti-O nanoclusters 10-50 nm in size are observed. High-temperature oxidation results show that the weight increases by 0.27 and $0.29mg/cm^2$ for the as-fabricated and heat-treated ($900^{\circ}C$) specimens, and by 0.47 and $0.50mg/cm^2$ for the as-fabricated and heat-treated ($1000^{\circ}C$) specimens, respectively. Further, after 24 h oxidation tests, the weight increases by 56.50 and $100.60mg/cm^2$ for the as-fabricated and heat-treated ($1100^{\circ}C$) specimens, respectively; the latter increase is approximately 100 times higher than that at $1000^{\circ}C$. Observation of the surface after the oxidation test shows that $Cr_2O_3$ is the main oxide on a specimen tested at $1000^{\circ}C$, whereas $Fe_2O_3$ and $Fe_3O_4$ phases also form on a specimen tested at $1100^{\circ}C$, where the weight increases rapidly. The high-temperature oxidation behavior of Fe-14Cr ODS steel is confirmed to be dominated by changes in the $Cr_2O_3$ layer and generation of Fe-based oxides through evaporation.