EFFECT OF SCANDIUM (SC) ADDITION IN GRAIN REFINING AND MECHANICAL PROPERTIES OF AL 18SI HYPEREUTECTIC ALLOY

• المؤلف الرئيسي: Ramadhani, Sri
• التنسيق: Final Project
• اللغة: Indonesia
• الوصول للمادة أونلاين: https://digilib.itb.ac.id/gdl/view/68826

Al-Si hypereutectic alloy plays an important role in the casting process, especially for piston, pump and high perfomance engines. This is supported by excellent castability and wear resistance. The use of this alloys is limited by the presence of Silicon crystal which reduces their machinabilty and strength. Modification and refinement which well-distributed phase lead to minimize this issues. This study made a similar alloy namely Al-18Si with Scandium (Sc) added using casting method which was studied and analyzed for its microstructure using optical and stereo microscope. SEM-EDS and XRD were used to determine the chemical composition of variations in addition of Scandium to Al-Si and phase confirmation. Measurement of grain size was carried out using ImageJ software and mechanical test such as tensile and hardness test was done. The addition of Sc as the initiator of heterogeneous nucleation decreased the sizes of primary silicon, SDAS, and eutectic silicon by 55%, 22.3%, and 33.65%, respectively. The homogenization process significantly reduces the size of the eutectic silicon by 70% and the aspect ratio of the eutectic silicon by 88%. The addition of Sc increased the ultimate strength, yield strength and elongation by 16%, 28%, and 66%, respectively, and decreased hardness value. The addition of Sc with homogenization process showed the value of strength and yield strength were relatively same but at % elongation showed an increasement of 135% and decreased value of each sample by 41%.