In this study, the effect of Sc addition on the microstructure and mechanical properties of Al-20Si alloys fabricated by extrusion of powders was investigated. The Al-Si-(Sc) powders produced by high pressure gas atomization were used in starting materials. The microstructure and structural characterization were performed by optical microscopy (OM), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with an energy dispersive X-ray spectroscopy (EDS). Mechanical properties of extruded bars were investigated by micro hardness test, tensile test and wear test. With increasing the Sc contents in Al-Si alloys, mechanical properties were significantly increased. These enhanced mechanical properties can be explained based on the refinement of primary Si due to the suppression of growth of primary Si by the well-surrounded and uniformly distributed Sc.
Keywords: Al-Si Alloys powder technology, gas atomizer, hypereutectic, scandium, Si particle.