Developing high-strength ferritic alloys reinforced by combination of hierarchical and laves precipitates

Ferritic steels are attractive as a candidate material for high temperature applications due to high thermal conductivity, low thermal expansion coefficient, and low cost compared to austenitic steels or Ni-based superalloys. Recently, Fe-Cr-Ni-Al-Mo(-Ti) ferritic alloys reinforced by B2-NiAl and/or B2-NiAl/L2(1)-Ni2TiAl hierarchical precipitates has been reported to improve the microstructural stability and mechanical properties at elevated temperatures. In the present study, we attempted to further improve the mechanical properties of the Fe-Cr-Ni-Al-Mo(-Ti) alloys strengthened by B2/L2(1) hierarchically-structured precipitates via introducing fine Laves phases. Specifically, Zr, Hf and Ta elements, which is well known to form the Laves phases, were added into previously studied Fe-Cr-Ni-Al-Mo(-Ti) ferritic alloys. The present study reveals that the combination of Laves phases and B2/L2(1) precipitates is effective in enhancing the mechanical properties of Fe-Cr-Ni-Al-Mo(-Ti) ferritic alloys at room and 973 K. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Ferritic steels are increasingly being considered as an ideal material for high temperature applications due to high thermal conductivity, low thermal expansion coefficient, and cost efficiency. The addition of Laves phases has been shown to enhance the mechanical properties of ferritic alloys, particularly at room temperature and 973K.