Strength, ductility, and fracture mode of ternary FeAl alloys
The iron aluminides Fe-45Al-5X-0.2B-0.1Zr (at. %), where X stands for the first row transition metals Ti, V, Cr, Mn, Fe, Co, Ni, Cu, were examined at room temperature for strength, ductility, environmental sensitivity, and fracture mode. The extruded materials were annealed at 1273 K to produce similar grain sizes and then at 673 K to reduce the quenched-in vacancies. All alloys were essentially single phase. Their solid-solution strengthening was found to correlate with the atomic size misfit from the lattice parameters. The ``binary`` alloy Fe-45Al-O.2B-0.1Zr exhibited predominantly transgranular fracture. Ternary alloying additions with atomic numbers less than that of Fe tended to enhance intergranular fracture, whereas those with atomic numbers higher than that of Fe favored substantial amounts of transgranular fracture. Tensile testing in a partial pressure of dry oxygen increased the ductilities of the ternary alloys only slightly, whereas the ductility of the binary alloy increased from about 8 to about 19%. The ductilities in air correlated inversely with the yield strength. However, those alloys exhibiting substantial amounts of transgranular fracture always showed higher ductilities than those fracturing intergranularly. The fracture results are interpreted in terms of yield strengths and ternary element site occupations.
- Research Organization:
- Oak Ridge National Lab., TN (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 46395
- Report Number(s):
- CONF-941144--125; ON: DE95010281
- Country of Publication:
- United States
- Language:
- English
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