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Nanocrystalline ODS-iron aluminide by cryo-milling: consolidation, microstructure and mechanical behavior

Sarma, S. Sudhakara; Prasad, Satya; Joardar, Joydip; Suresh, K.; Reddy, A. V.; Vijay, R.

By 27 January 2020 July 27th, 2020 No Comments

Materials Research Express, 2019, vol 6, 10, pp. 106572

DOI:10.1088/2053-1591/ab3814

Abstract

Nanocrystalline oxide dispersion strengthened (ODS) Fe-25 at% Al alloy was produced by cryo-milling of elemental powder blend and Y2O3. The as-milled powder was consolidated by hot extrusion. The Microstructure and mechanical properties of the consolidated material were evaluated. Fracture of powder particles during milling was dominant due to cryo temperatures which transform the material from ductile to brittle. Complete dissolution of Al in Fe was observed after 10 h of milling. Hot extruded and annealed sample showed fine grained structure with average grain size of 450 nm along with fine Y2O3, Al2O3 and AlN particles. The fabricated iron aluminide exhibited considerably high compressive yield strength of 1300 MPa with a ductility of 25%. Such improved mechanical behavior could be correlated to the fine particle size and ultrafine crystallite size of the milled powder evolved under cryo-milling, which eventually led to the formation of ultrafine grain microstructure. Cry milling also ensured uniform distribution of the nanosized Y2O3 dispersoids and formation of other nanosized particles like Al2O3 and AlN, which contributed to enhanced mechanical properties.

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