The role of dispersoids in maintaining the corrosion resistance of mechanically alloyed oxide dispersion strengthened alloys

Journal Article · Mon May 15 04:00:00 EDT 1995 · Scripta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-716X(95)00240-V· OSTI ID:69649

Cama, H; Hughes, T A ^[1]

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1. Univ. of Leeds (United Kingdom). School of Materials

Amongst the various commercial mechanically alloyed (MA) oxide dispersion strengthened (ODS) alloys available, ferritic alloys are most suitable for use at temperatures exceeding 1,100 C, since {gamma}{prime} particle dissolution results in the loss of strength of nickel based MA ODS alloys. In commercial MA ODS alloys, yttria particles are commonly added in the starting powers, and it is well known that they are not retained in the final product because they react with aluminum and oxygen present in the system during thermomechanical processing and form mixed (Y,Al) oxide particles. In this paper the role of (Y,Al) oxide particles in maintaining the overall aluminum concentration in the matrix necessary to repair the outer oxide scale is discussed. It is well known that during exposure in air, aluminum is lost from the bulk of MA ODS alloys to the growth of a surface alumina film. The extent of aluminum lost is dependent on the section thickness and can significantly affect the volume fraction of the aluminum rich dispersoids. Coarsening of the dispersoids at temperatures up to 1,200 C in the thick MA 956 bar occurs without significant aluminum loss, while their volume fraction increases continuously. However, coarsening of the dispersoids in the thinner ODM 751 tube at 1,200 and 1,300 C is accompanied by dissolution of the dispersoid particles in order to maintain the aluminum concentration in the matrix.

• OSTI ID: 69649
• Journal Information: Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 10 Vol. 32; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AIR
ALUMINIUM ALLOYS
CHROMIUM ALLOYS
CORROSION RESISTANCE
DISPERSIONS
DISSOLUTION
ELECTRON MICROPROBE ANALYSIS
IRON BASE ALLOYS
MOLYBDENUM ALLOYS
SAMPLE PREPARATION
SCALING
TEMPERATURE RANGE 1000-4000 K
TITANIUM ADDITIONS
TRANSMISSION ELECTRON MICROSCOPY
YTTRIUM OXIDES