Microstructure and mechanical properties of automotive components die cast with secondary aluminum alloys by SEED semi-solid process

The microstructure and mechanical properties of an automotive component die-cast by Swirled Enthalpy Equilibration Device process are analyzed. Two secondary aluminum alloys have been used, AlSi7Cu3Mg and AlSi9Cu3(Fe) alloys. The castings have been investigated by means of computer tomography to evaluate the concentration and distribution of casting defects, especially in the regions of thick wall thickness. Microstructural investigation has been carried out by means of optical microscope and image analysis technique. The results reveal a not uniform distribution of primary α-Al globules throughout the casting, with a solid fraction ranging from 48 to 58%, and eutectic segregation phenomena. The castings have been mapped in terms of mechanical properties and quality index. The variation of the mechanical properties reflects the presence of local casting defects and alloying segregation.