Ferritic Alloys with Extreme Creep Resistance via Coherent Hierarchical Precipitates

Gian Song, Zhiqian Sun, Lin Li, Xiandong Xu, Michael Rawlings, Christian H. Liebscher, Bjørn Clausen, Jonathan Poplawsky, Donovan N. Leonard, Shenyan Huang, Zhenke Teng, Chain T. Liu, Mark D. Asta, Yanfei Gao, David C. Dunand, Gautam Ghosh, Mingwei Chen, Morris E. Fine, Peter K. Liaw*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

73 Scopus citations

Abstract

There have been numerous efforts to develop creep-resistant materials strengthened by incoherent particles at high temperatures and stresses in response to future energy needs for steam turbines in thermal-power plants. However, the microstructural instability of the incoherent-particle-strengthened ferritic steels limits their application to temperatures below 900 K. Here, we report a novel ferritic alloy with the excellent creep resistance enhanced by coherent hierarchical precipitates, using the integrated experimental (transmission-electron microscopy/scanning-transmission-electron microscopy, in-situ neutron diffraction, and atom-probe tomography) and theoretical (crystal-plasticity finite-element modeling) approaches. This alloy is strengthened by nano-scaled L2 1 -Ni 2 TiAl (Heusler phase)-based precipitates, which themselves contain coherent nano-scaled B2 zones. These coherent hierarchical precipitates are uniformly distributed within the Fe matrix. Our hierarchical structure material exhibits the superior creep resistance at 973 K in terms of the minimal creep rate, which is four orders of magnitude lower than that of conventional ferritic steels. These results provide a new alloy-design strategy using the novel concept of hierarchical precipitates and the fundamental science for developing creep-resistant ferritic alloys. The present research will broaden the applications of ferritic alloys to higher temperatures.

Original languageEnglish (US)
Article number16327
JournalScientific reports
Volume5
DOIs
StatePublished - Nov 9 2015

ASJC Scopus subject areas

  • General

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