Microstructure and mechanical properties of rapidly solidified and extruded Al-20Si alloy with extrusion direction

摘要

The effect of extrusion direction on the microstructure and mechanical properties of Al-20Si alloys, manufactured by gas atomization followed by degassing and hot extrusion, was studied by a combination of optical microscopy, scanning electron microscopy, X-ray diffraction, compressive strength testing and wear testing. The microstructure of the extruded bars showed a homogeneous distribution and different primary Si size and shape embedded in the Al matrix depending on the extrusion direction. As the extrusion direction changes from diagona 1, perpendicular to parallel section, the yield strength is increased from 219MPa, 225MPa to 263MPa respectively. The specific wear decreased significantly at all sliding speeds for the parallel section in comparison to the perpendicular and diagonal sections.