The influence of trace amounts of elements additions to Al-Si alloys of SIMA processing

As it known, since dendritic grain structure is generates a great resistance for solid forming, spherical grain structure has a great importance for in this type forming. One of the procedures of transforming the grain structure from dendritic form to spherical form is SIMA (Stress Induced Melt Activated) process which is also known as recrystallization method. In this study, information about the characteristics of aluminum and its alloys were presented. The ETIAL 180 alloy and SIMA process was introduced. By adding trace amount of Mg and SN via gravity casting method, samples were obtained. After examining the microstructures and hardness of the samples, the microstructure and hardness values of these samples were analyzed by subjecting them to SIMA process. The SEM and WRD analyzes of the samples were performed and the results were compared. It was observed that the Mg and SN elements trace amount of which were added to ETIAL 180 aluminum alloy has no effect on sphericity and grain size with SIMA method. It was observed that the sphericity of the dendritic structure which was cracked by using the SIMA method was close to perfection. It was detected that the addition of Mg element had increased the hardness value by 20% while addition of Sn element had no significant effect on hardness value. Since semi-solid forming was not performed following the SIMA process, a decrease was observed in the hardness value of SIMA processed samples. It was observed that the insertion of Mg and Sn elements trigged the formation of the Chinese script shaped intermetallic, and formation of Mg2Si compound occurred with addition of Mg element. It was observes that these Chinese script shaped intermetallic coarsened, cracked and split to matrix structures by breaking with use of SIMA method. Keywords: SIMA process, ETIAL 180 alloy, Al-Si alloys, XRD, SEM