SIMA prosesiyle üretilmiş ETİAL 180 alüminyum alaşımına eser miktarlarda magnezyum ve kalay ilavesinin etkilerinin incelenmesi

It has been recognized that semisolid processing (SSP) offers several advantages over casting, forging and powder metallurgy techniques. The key to the SSP of alloys lies in the unique microstructures of the feedstock materials in which the solid particles are spheroidal in shape as opposed to the typical dendritic microstructures of cast alloys. A non-dendritic structure behaves as a ‘thixotropic’ slurry. When they are sheared, they readily flow. SIMA process has advantages on other SSP process because it is simple process and it does not require complex equipments. In the SIMA method, the predeformed material is first heated to the semi-solid range. As it nears the solidus temperature, the grains recrystallize to form a fine grain structure. After the solidus temperature is passed, the grain boundaries melt to form the SSP microstructure. Al-Si alloys are widely used because of their excellent combination of properties, including good castability, corrosion and wear resisntance. Their solid mechanical and physical properties have been studied extensively. It is well-known that trace elements can change eutectic silicon morphology and refine primary silicon crystal, hence a number of properties like ultimate tensile strenght, ductility, wear resistance are improved obviously. A range of different intermetallic phases may form during solidification, depending on alloy composition and solidification condition. Relative volume fraction, chemical composition and morphology of structural constituents have significant influence on their useful properties. In this study, trace amounts of Mg and Sn elements were added to ETİAL180 alloy. The effects of trace elements on ETİAL 180 alloy were investigated. At the same time, the effect of the trace elements on SIMA process were evaluated. The samples were studied by means of metallographic examinations, the hardness tests were applied and the detailed examinations were done by XRD analyses. It was obtained that while Sn addition caused to slighltly decrease in materials hardness, Mg addition increased the hardness. It was observed that Sn addition didn’t produce new compounds or intermetallics, it was in solid solution of the aluminum. On the other hand, Mg addition into ETIAL 180 alloy produced the Mg2Si intermetallics. SIMA process resulted in changes from dendritic to globular structure. At the same time, it didn’t yield to any new compound or intermetallics. SSP generally improves mechanical properties due to loading during forming process. The loading causes to decrease of porosity and refine the grains. In this study, ETIAL 180 was investigated while it was cooled to room temperature from semi-solid range, however forming process wasn’t applied. Therefore, it wasn’t obtained expected mechanical results.