| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1578138 | Materials Science and Engineering: A | 2011 | 7 Pages |
Twenty-five samples of commercially available, gas-atomised Al (99.5%) powders with particle sizes <10 μm were hot extruded into Al–Al2O3 composites formed in situ during extrusion. The effect of particle size, surface area, oxygen content and atomisation atmosphere of the powder on the microstructure and mechanical properties of the extruded compacts were studied by Brunauer, Emmett, Teller (BET) analysis, hot gas extraction, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and tensile tests. Thermal stability of the compacts and the individual strengthening mechanisms operating in the compacts were discussed. It was found that the properties of the compacts stemmed from the extraordinary grain boundary strengthening effect of the ultrafine-grained compacts due to their microstructures. The efficiency of the grain boundary strengthening was significantly enhanced by the presence of nano-metric Al2O3 dispersoids introduced in situ. The strength of the compacts was closely related to the surface area of the powder particles. In addition, the entrapped gasses and chemically bonded humidity had a negative effect on the mechanical properties of the compacts.
► 25 gas atomised Al 99.5% powders with particle size <10 μm were hot extruded. ► The strength of compacts was closely related to powder surface area. ► Grain boundary strengthening was enhanced by the presence of in situ Al2O3 dispersoids. ► Compacts showed good thermal stability due to grain pinning of Al2O3 dispersoids.
