Effect of chromium on the environmental sensitivity of FeA1 at room temperature

Journal Article · Mon Dec 14 23:00:00 EST 1992 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(92)90027-C· OSTI ID:6799286

Klein, O; Baker, I ^[1]

---

1. Dartmouth Coll., Hanover, NH (United States). Thayer School of Engineering

It is now recognized that the room temperature ductility of polycrystalline B2-structured FeAl is influenced by both intrinsic and extrinsic factors. It has also been shown that the ductility of iron-rich FeAl depends on extrinsic factors such as test environment and heat treatment. It has been suggested that the embrittlement of FeAl is due to atomic hydrogen arising from a reaction between water vapor and aluminum atoms at crack tips. The hydrogen atoms drive into the metal and thereby cause crack propagation. Since the hydrogen diffusion is time-dependent, there will presumably be a strain-rate dependence of the ductility. Such behavior was confirmed by tests on Fe-45Al in air at strain rates varying from 1 [times] 10[sup [minus] 6] s[sup [minus] 2] to 1 s[sup [minus] 1]. The elongation was shown to be independent of strain rate (at [approximately] 3%) up to 1 [times] 10[sup [minus] 2]s[sup [minus] 1], but increased at faster strain rates and finally appeared to level off at [approximately] 9% at 1 s[sup [minus] 1]. A brittle to ductile transition took place between strain rates of 10[sup [minus] 2] and 10[sup [minus] 1] s[sup [minus] 1], but there was no change in fracture mode. This paper reports on a study performed to examine the effect of replacing some Al (5 at. %) in Fe-45Al with Cr on the strain rate dependence of the tensile ductility and fracture behavior of this intermetallic. The tensile tests were performed on material which had been given a low-temperature (400[degrees]C vacancy-removing anneal.

• OSTI ID: 6799286
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 27:12; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
080800 -- Hydrogen-- Properties & Composition
36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
360104 -- Metals & Alloys-- Physical Properties
ALLOYS
ALUMINIUM ALLOYS
ANNEALING
BORON ADDITIONS
BORON ALLOYS
CHROMIUM ADDITIONS
CHROMIUM ALLOYS
CRACK PROPAGATION
CRYSTALS
DOPED MATERIALS
DUCTILITY
EMBRITTLEMENT
FRACTURE PROPERTIES
HARDENING
HEAT TREATMENTS
HYDROGEN EMBRITTLEMENT
INTERMETALLIC COMPOUNDS
IRON ALLOYS
MATERIALS
MECHANICAL PROPERTIES
PERFORMANCE TESTING
POLYCRYSTALS
STOICHIOMETRY
STRAIN HARDENING
TEMPERATURE EFFECTS
TENSILE PROPERTIES
TESTING