Anomalous temperature dependence of flow stress in a Fe{sub 3}Al alloy
Iron aluminides have attracted much interest since 1930s when the excellent corrosion resistance was noted in alloys with the composition of more than about 18 at.% Al. These alloys have relatively low material cost, due to the reduced usage of strategic elements like Cr, Mo and Ni, and a lower density than stainless steels. Their tensile strength is also comparable to those of ferritic and austenitic steels. These advantages have led the iron aluminide alloys being considered for many applications in industries needing sulfidation and oxidation resistance (1). However, the poor ductility at ambient temperatures and an abrupt drop in strength above 600 C have limited these alloys for structural applications. In the past years, extensive efforts have been devoted to understanding and improving the metallurgical properties of iron aluminides with the aim of producing more strong, ductile, and corrosion-resistant materials for structural applications. These studies have resulted in significant contributions to the understanding of the fabrication and mechanical properties of iron aluminides. Deformation behavior in iron aluminides is now known to depend on composition, temperature, and the presence or absence of ordered structures. Recent studies have demonstrated that improved engineering ductility of 10--15% can be achieved in wrought Fe{sub 3}Al-based iron aluminide alloys, through the control of composition and microstructure. The effect of strain rate on the deformation behavior of Fe{sub 3}Al alloys, especially on the anomalous temperature dependence of strength is of interest recently and more systematic investigation is now necessitated. Load relaxation test has been generally regarded as a very effective technique to measure the strain rate sensitivity over a wider range of strain rates with very little microstructural changes and has been applied to the plasticity of various rate-sensitive materials. In the present study, the iron aluminide alloys with 27.6 at.% Al having the various single-phase field, i.e. the disordered solid solution ({alpha}), an Fe{sub 3}Al with an imperfectly ordered B2 structure, and an ordered Fe{sub 3}Al with the D0{sub 3} structure were first prepared. A series of load relaxation tests was then carried out at the various temperatures ranging from 300 to 800 C to investigate the effect of the tensile strain rate on the anomalous flow behavior.
- Research Organization:
- Research Inst. of Industrial Science and Technology, Pohang (KR)
- OSTI ID:
- 20013342
- Journal Information:
- Scripta Materialia, Vol. 42, Issue 3; Other Information: PBD: Jan 2000; ISSN 1359-6462
- Country of Publication:
- United States
- Language:
- English
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