Multi-Phase Cr-Based Alloys for Aggressive High Temperature Environments
The objective of this work is to develop and characterize a new family of Cr-based alloys for structural use in aggressive 900-1300 C corrosion environments. The potential advantages of Cr are high melting point, moderate density, and good high-temperature corrosion resistance in many environments [1]. However, these are currently negated by inadequate high-temperature strength, ambient-temperature brittleness, and susceptibility to environmental embrittlement at elevated-temperatures by rapid nitride subscale formation [1]. Over the course of this effort, two distinct approaches to overcoming these problems have been pursued: Cr{sub 2}Ta-reinforced Cr, and MgO-dispersed Cr. The Cr{sub 2}Ta-reinforced Cr alloys are based on the Cr-Cr{sub 2}Ta eutectic structure and contain a Cr solid solution matrix phase reinforced with lamellar Cr{sub 2}Ta Laves phase. They exhibit an attractive combination of high-temperature strength (tensile fracture strengths of 340-550 MPa at 1200 C), high-temperature ductility (15-40% tensile elongation above 1000 C), creep resistance (creep rupture life in excess of 1000 hours at 138 MPa loading at 1000 C in air), and oxidation resistance (comparable to that of commercial chromia-forming alloys in 1100 C, 1000 h cyclic oxidation screenings in air) [2]. However, no room-temperature ductility has been achieved and extensive microalloying and microstructural control efforts have 1ed to only modest room-temperature fracture toughness of 12-14 MPa {radical}m.
- Research Organization:
- Oak Ridge National Lab., Oak Ridge, TN (US)
- Sponsoring Organization:
- USDOE Office of Fossil Energy (FE) (US)
- OSTI ID:
- 835703
- Country of Publication:
- United States
- Language:
- English
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