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Title: The influence of processing on microstructure and properties of iron aluminides

Abstract

Oxide dispersion strengthened (ODS) iron aluminide alloys based on Fe3Al have been formed by reaction synthesis from elemental powders followed by hot extrusion. The resulting alloys have approximately 2.5% by volume Al{sub 2}O{sub 3} particles dispersed throughout the material. A proper combination of extrusion temperature, extrusion ratio, and post-consolidation heat treatment results in a secondary recrystallized microstructure with grain sizes greater than 25mm. ODS material with 5% Cr addition exhibits approximately an order of magnitude increase in time to failure at 650 C compared to a similar alloy without the oxide dispersion. Addition of Nb and Mo along with Cr results in decreased minimum creep rates, however, the time to rupture is greatly reduced due to fracture at low strains initiated at large Nb particles that were not put into solution. The activation energy for creep in the 5% Cr ODS material is on the order of 210 kJ/mole and the power law creep exponent is 9--9.5. Transmission electron microscopy examination of the substructure of deformed samples indicates some formation of low angle dislocation boundaries, however, most of the dislocations are pinned at particles. The TEM observations and the value of the creep exponent are indicative of dislocation breakaway frommore » particles as the rate controlling deformation mechanism. The TEM results indicate that particles smaller than about 100nm and larger than about 500 nm do not contribute significantly to dislocation pinning.« less

Authors:
; ;  [1]
  1. Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
OSTI Identifier:
330676
Report Number(s):
CONF-9705115-PROC.; ORNL/FMP-97/1
ON: DE98007329; TRN: IM9915%%193
Resource Type:
Conference
Resource Relation:
Conference: 11. annual conference on fossil energy materials, Knoxville, TN (United States), 20-22 May 1997; Other Information: PBD: Dec 1997; Related Information: Is Part Of Proceedings of the eleventh annual conference on fossil energy materials; Judkins, R.R. [comp.]; PB: 419 p.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; IRON BASE ALLOYS; ALUMINIUM ALLOYS; MICROSTRUCTURE; DISPERSION HARDENING; EXTRUSION; ALUMINIUM OXIDES; HEAT TREATMENTS; GRAIN SIZE; METALLURGICAL EFFECTS; CHROMIUM; NIOBIUM; MOLYBDENUM; CREEP; DISLOCATION PINNING

Citation Formats

Wright, R N, Wright, J K, and Anderson, M T. The influence of processing on microstructure and properties of iron aluminides. United States: N. p., 1997. Web.
Wright, R N, Wright, J K, & Anderson, M T. The influence of processing on microstructure and properties of iron aluminides. United States.
Wright, R N, Wright, J K, and Anderson, M T. 1997. "The influence of processing on microstructure and properties of iron aluminides". United States. https://www.osti.gov/servlets/purl/330676.
@article{osti_330676,
title = {The influence of processing on microstructure and properties of iron aluminides},
author = {Wright, R N and Wright, J K and Anderson, M T},
abstractNote = {Oxide dispersion strengthened (ODS) iron aluminide alloys based on Fe3Al have been formed by reaction synthesis from elemental powders followed by hot extrusion. The resulting alloys have approximately 2.5% by volume Al{sub 2}O{sub 3} particles dispersed throughout the material. A proper combination of extrusion temperature, extrusion ratio, and post-consolidation heat treatment results in a secondary recrystallized microstructure with grain sizes greater than 25mm. ODS material with 5% Cr addition exhibits approximately an order of magnitude increase in time to failure at 650 C compared to a similar alloy without the oxide dispersion. Addition of Nb and Mo along with Cr results in decreased minimum creep rates, however, the time to rupture is greatly reduced due to fracture at low strains initiated at large Nb particles that were not put into solution. The activation energy for creep in the 5% Cr ODS material is on the order of 210 kJ/mole and the power law creep exponent is 9--9.5. Transmission electron microscopy examination of the substructure of deformed samples indicates some formation of low angle dislocation boundaries, however, most of the dislocations are pinned at particles. The TEM observations and the value of the creep exponent are indicative of dislocation breakaway from particles as the rate controlling deformation mechanism. The TEM results indicate that particles smaller than about 100nm and larger than about 500 nm do not contribute significantly to dislocation pinning.},
doi = {},
url = {https://www.osti.gov/biblio/330676}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1997},
month = {12}
}

Conference:
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