Abstract
A new Fe-Cr-Al (FCA) alloy system has been developed with good oxidation resistance and creep strength at high temperature. The alloy system is a candidate for use in future fossil-fueled power plants. The creep strength of these alloys at 973 K (700 °C) was found to be comparable with traditional 9 pct Cr ferritic–martensitic steels. A few FCA alloys with general composition of Fe-30Cr-3Al-.2Si-xNb (x = 0, 1, or 2) with a ferrite matrix and Fe2Nb-type Laves precipitates were prepared. The detailed microstructural characterization of samples, before and after creep rupture testing, indicated precipitation of the Laves phase within the matrix, Laves phase at the grain boundaries, and a 0.5 to 1.5 μm wide precipitate-free zone (PFZ) parallel to all the grain boundaries. In these alloys, the areal fraction of grain boundary Laves phase and the width of the PFZ controlled the cavitation nucleation and eventual grain boundary ductile failure. A phenomenological model was used to compare the creep strain rates controlled by the effects of the particles on the dislocations within the grain and at grain boundaries. (The research sponsored by US-DOE, Office of Fossil Energy, the Crosscutting Research Program).
Original language | English |
---|---|
Pages (from-to) | 4598-4614 |
Number of pages | 17 |
Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
Volume | 48 |
Issue number | 10 |
DOIs | |
State | Published - Oct 1 2017 |
Funding
The authors thank Dr. Xinghua Yu and Thomas Muth at Oak Ridge National Laboratory for their comments on this manuscript. Research sponsored by the Crosscutting Research Program, Office of Fossil Energy, U.S. Department of Energy. A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.
Funders | Funder number |
---|---|
U.S. Department of Energy | |
Office of Fossil Energy |