Microstructure and mechanical properties of bulk nanocrystalline Al–Fe alloy processed by mechanical alloying and spark plasma sintering

Nanocrystalline Al–5 at.% Fe alloy powders produced by mechanical alloying were consolidated by spark plasma sintering. The sintered sample showed high strength >1000 MPa with a large plastic strain of 15% at room temperature and 500 MPa at 350 °C. Microstructure characterizations by transmission electron microscopy and atom probe tomography revealed that the sintered samples are composed of α-Al and Al6Fe nanocrystalline regions with 90 nm in diameter and a minor fraction of Al13Fe4 phase and coarsened 0.5–1 μm α-Al grains. This bimodally grained feature is attributed to the relatively large plastic strain for the strength level of 1000 MPa at room temperature.