Investigation of mechanical properties of ODS Fe40Al sinters
Tomasz Durejko, Zbigniew Zarański, Stanisław Sulej Wojskowa Akademia Techniczna, Wydział Mechaniczny, Instytut Materiałoznawstwa i Mechaniki Technicznej, ul. Kaliskiego 2, 00-908 Warszawa
Quarterly No. 2, 2005 pages 39-42
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abstract The iron aluminides FeAl have been among the most widely investigated intermetallics. For example, they have relatively low density, high stiffness, and excellent resistance to oxidation and corrosion at elevated temperature. Their major disadvantages is the susceptibility to environmental embrittlement at room temperature, very poor strength and creep resistance above 600oC. This problem can be partially solved by microalloying and oxide dispersion strengthening (ODS). Oxide dispersion strengthening (ODS) iron aluminides alloys based on FeAl have been formed by two stages sintering process. The elemental iron and aluminum powders with addition of nanometer size Al2O3 (1 wt.%) were mixed together to give a composition of Fe-40 at.% Al by ball milling. Three variants of powders mixture size: 40÷38, 53÷38, < 38 μm were used. The initial stage of manufacturing was mechanical forming of prepared mixture by pressing at elevated temperature. Two value of cyclic pressure frequency was used - static version (0 Hz) and 40 Hz. Second stage of manufacturing led to change of chemically and structurally heterogeneous pre-sintered materials into homogeneous Fe40Al-based intermetallics. Changes in mechanical properties of sintered materials were studied. The essential strength parameters of intermetallic sinters were calculated on the base of stress-strain compression curves. Influence of mixture powders size on compression strength and equivalent strain was analysed. It was stated that size of powders influence on sinters compression strength. With increase powders dimensionally range increase value of Rc too. Samples obtained from < 38 μm powders, consolidated by static pressure have the highest strength of the order of 2482 MPa at 42% strain. Kind of used loading has a negligible effect on sinter strength. However, cyclic loading decrease in plastic deformation. Decrease about ten percent in equivalent strain was observed for all variants. Key words: Fe40Al intermetallics phase, ODS (oxide dispersion-strengthened) sinters, compression test