SYNTHESIS, PROCESSING, AND DEFORMATION OF BULK NANOPHASE FE-28A1-2CR INTERMETALLIC

Nanophase Fe-28Al-2Cr powder was obtained by ball milling and consolidated by shock wave compaction. Fully-dense well-bonded compacts were produced with a diameter of 32 mm and a thickness of almost-equal-to 6 mm. The grain size in the compacts was almost-equal-to 80 nm. In tension, the nanophase intermetallic is brittle with a failure strength (sigma(f) = 0.65 GPa) comparable to a coarse-grained intermetallic with similar composition. In compression, the nanophase material exhibits superplastic-like flow during room temperature quasistatic deformation to true strains greater than 1.4. The compressive flow strength is 2.1 GPa and no macroscopic strain hardening is observed. This behavior is compared to the coarse-grained material that has a yield strength of 0.25 GPa, displays significant work hardening and little tension-compression anisotropy. TEM examination of the nanophase material before and after deformation shows a refinement of the microstructure during deformation. The microstructure refines to almost-equal-to 10 nm grains surrounded by amorphous material.