Alloy development of FeAl aluminide alloys for structural use in corrosive environments
Objectives include adequate ductilities ([ge]10%) at ambient temperature, high-temperature strength better than stainless steels (types 304 and 316), and fabricability and weldability by conventional techniques (gas tungsten arc). The alloys should be capable of being corrosion resistant in molten nitrate salts with rates lower than other iron-base structural alloys and coating materials (such as Fe-Cr-Al alloys). Such corrosion rates should be less than 0.3 mm per year. The FeAl aluminide containing 35.8 at. % Al was selected as base composition. Preliminary studies indicate that additions of B and Zr, increase the room-temperature ductility of FeAl. Further alloying with 0.2% Mo, and/or 5% Cr, improves the creep. Our preliminary alloying effort has led to identification of the following aluminide composition with promising properties: Fe - (35 [plus minus] 2)Al - (0.3 [plus minus] 0.2)Mo - (0.2 [plus minus] 0.15)Zr - (0.3 [plus minus] 0.2)B- up to 5Cr, at. %. However, this composition is likely to be modified in future work to improve the weldability of the alloy. The FeAl alloy FA-362 (Fe-35.8% Al-0.2% Mo-0.05% Zr-0.24% B) produced by hot extrusion at 900C showed a tensile ductility of more than 10% at room temperature and a creep rupture life longer than unalloyed FeAl by more than an order of magnitude at 593C at 138 MPa. Melting and processing of scaled-up heats of selected FeAl alloys are described. Forging, extruding, and hot-rolling processes for the scale-up heats are also described.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 6136151
- Report Number(s):
- ORNL/TM-12199; ON: DE93015100
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALUMINIUM ALLOYS
CORROSION RESISTANCE
CORROSION RESISTANT ALLOYS
IRON BASE ALLOYS
BORON ADDITIONS
CHROMIUM ADDITIONS
CREEP
FABRICATION
MECHANICAL PROPERTIES
MICROSTRUCTURE
MOLTEN SALTS
MOLYBDENUM ADDITIONS
OXIDATION
ZIRCONIUM ADDITIONS
ALLOYS
BORON ALLOYS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
IRON ALLOYS
MOLYBDENUM ALLOYS
SALTS
ZIRCONIUM ALLOYS
360105* - Metals & Alloys- Corrosion & Erosion