Influence of scandium addition on the high-temperature grain size stabilization of oxide-dispersion-strengthened (ODS) ferritic alloy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 636; no. C; pp. 565 - 571
• Main Authors: Li, Lulu, Xu, Weizong, Saber, Mostafa, Zhu, Yuntian, Koch, Carl C., Scattergood, Ronald O.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2015; Elsevier
• Subjects: Alloying additive; Dispersion hardening alloys; Grain size; Materials science; Mechanical alloying; Microstructure; Nanostructure; Oxide-dispersion-strengthened alloy; Sc stabilization; Scandium; Stabilization; Thermal stability; Oxide-dispersion-strengthened alloy; Mechanical alloying; Sc stabilization; Thermal stability
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2015.03.117

The influence of 1–4at% Sc addition on the thermal stability of mechanically alloyed ODS ferritic alloy was studied in this work. Sc addition was found to significantly stabilize grain size and microhardness at high temperatures. Grain sizes of samples with 1 and 4at% Sc was found maintained in the nanoscale range at temperatures up to 1000°C with hardness maintained at 5.6 and 6.7GPa, respectively. The detailed microstructure was also investigated from EDS elemental mapping, where nanofeatures [ScTiO] were observed, while nanosized [YTiO] particles were rarely seen. This is probably due to the concentration difference between Sc and Y, leading to the formation of [ScTiO] favoring that of [YTiO]. Precipitation was considered as the major source for the observed high temperature stabilization. In addition, 14YT–Sc alloys without large second phases such as Ti-oxide can exhibit better performance compared to conventional ODS materials.