CCS and Power Systems

Crosscutting Research - Plant Optimization Technologies


Computational Design of Creep-Resistant Alloys and Experimental Validation in Ferritic Superalloys


Performer: University of Tennessee

Project No: FE0005868


Accomplishments


Researchers have developed a Calculation of Phase Diagrams (CALPHAD) model of the aluminum-nickel-titanium (Al-Ni-Ti) system. The results of this model compare favorably to known phases and results of other modeling approaches. Researchers have calculated coherent interfacial energies involving intermetallic precipitates in iron-nickel-titanium-aluminum (Fe-Ni-Ti-Al) superalloys using first-principles methods. This data helps in the understanding and future modeling of the behavior of these alloys in advanced energy systems.

Researchers have initiated a systematic compression creep study of a complex alloy system known as FBB8 [Fe-6.5Al-10Cr-10Ni-3.4Mo-0.25Zr-0.005B, weight percent (wt.%)]. They have built upon the work of previous studies of the FBB8 alloy by investigating the creep properties of FBB8 with titanium additions of 2 and 6 wt.%. Several valuable results were obtained from this study. Both FBB8+2%Ti and FBB8+6%Ti were found to be more creep resistant at 700°C than the previously studied FBB8 alloy. At a given stress, the creep strain rate of the FBB8+6%Ti is approximately 10–50 times lower than that of the FBB8 alloy. The creep strain rate of the FBB8+2%Ti is three orders of magnitude lower, compared to the FBB8 alloy [in the stress range from 140 to 170 megapascals (MPa)]. In addition, significant increases in the threshold stress, below which no measureable creep strain is obtained in the laboratory time-scale, were observed in both Ti-bearing alloys. The threshold stress improves from 69 MPa in the FBB8 alloy to 100 and 140 MPa in the FBB8+6%Ti and FBB8+2%Ti alloys, respectively.


Project Details