Measurement of the critical level of moisture for initiation of water-vapor-induced environmental embrittlement in a Fe[sub 3]Al-based alloy

Conference · Wed Jan 01 00:00:00 EST 1992

OSTI ID:6859130

McKamey, C G; Lee, E H

Iron aluminides based on Fe[sub 3]Al are of interest as structural materials because of their excellent corrosion resistance in many environments. However, studies have shown that one of the major causes of low room temperature tensile ductility, which so far has limited the use of these alloys, is an environmental reaction involving aluminum in the presence of water vapor. During this reaction, atomic hydrogen is released, moves into the sample ahead of the crack tip during stressing, and causes failure before the true ultimate tensile strength of the material is reached. This reaction is reduced significantly by testing in oxygen or vacuum. In the present study, an Fe[sub 3]Al-based alloy was tensile tested as a function of the level of water vapor in the test environment, from a vacuum of 10[sup [minus]4] Pa to a water vapor partial pressure of 1330 Pa. The results show that a water vapor level of as low as 133 Pa (1 torr) can result in significant embrittlement. The fracture mode remains transgranular cleavage, but the scale of the cleavage facets changes with the water vapor level.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6859130
• Report Number(s): CONF-921101-10; ON: DE93004104
• Resource Relation: Conference: Material Research Society fall meeting, Boston, MA (United States), 30 Nov - 5 Dec 1992
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
INTERMETALLIC COMPOUNDS
CORROSION RESISTANCE
EMBRITTLEMENT
MECHANICAL PROPERTIES
CONTROLLED ATMOSPHERES
MEASURING METHODS
ALUMINIUM ALLOYS
IRON ALLOYS
MOISTURE
TENSILE PROPERTIES
WATER VAPOR
ALLOYS
ATMOSPHERES
FLUIDS
GASES
VAPORS
360105* - Metals & Alloys- Corrosion & Erosion
360103 - Metals & Alloys- Mechanical Properties