Section-dependent microstructure and mechanical properties of rapidly solidified and extruded Al–20Si alloy

The microstructure and mechanical properties of rapidly solidified and extruded Al–20Si alloys were studied by a combination of optical microscopy, scanning electron microscopy, X-ray diffraction, compression testing, and wear testing. The microstructure of the extruded bars showed a homogeneous distribution of different primary Si sizes and shapes embedded in the Al matrix depending on the section considered in the extruded bar. As the section changes from diagonal through perpendicular to parallel, the compressive yield strength increased from 219 through 225 to 263 MPa, respectively. The specific wear was the lowest at all sliding speeds for the parallel section in comparison to the perpendicular and diagonal sections of the extruded bar.