Improvement of structure and properties of AlSi11 alloy using new generation grain refiners

Aluminum-Silicon alloys are frequently preferred due to their low weight, good castability, low cost and mechanical properties. Due to their high strength, wear resistance and corrosion resistance properties, they are widely used in automotive or aircraft applications. Mechanical properties can be improved with the addition of grain refiners in aluminum alloys. As a result of grain size refinement, high strength, good wear resistance and toughness can be achieved. At the same time, the fine grain size allows for a homogeneous microstructure. This prevents pore formation and segregation and improves corrosion resistance. The effect of grain refinement on mechanical properties is due to the change in the distribution of second phase particles. Titanium (Ti) and Boron (B) have traditionally been used for grain refinement in aluminum alloys. When Ti is added to the alloy, it forms a TiAl3 compound with aluminum and creates heterogeneous nucleation points in liquid aluminum. Today, research is also being conducted on the use of new generation grain refiners. Niobium (Nb) - Boron (B) alloys are used as new generation grain refiners. The fact that the lattice structures of Al3Nb and NbB2 alloys are very close to Al3Ti and TiB2 alloys gives these alloys an advantage to be a grain refiner candidate. In the thesis study, grain refiners were added to AlSi alloy at different parameters, including conventional and new generation grain refiners. After the additions, microstructure, hardness, wear, tensile, yield and elongation properties of the non-added and added alloys were compared. In addition, liquid metal quality was evaluated by bifilm calculations. Aluminum-Silicon alloys are frequently preferred due to their low weight, good castability, low cost and mechanical properties. Due to their high strength, wear resistance and corrosion resistance properties, they are widely used in automotive or aircraft applications. Mechanical properties can be improved with the addition of grain refiners in aluminum alloys. As a result of grain size refinement, high strength, good wear resistance and toughness can be achieved. At the same time, the fine grain size allows for a homogeneous microstructure. This prevents pore formation and segregation and improves corrosion resistance. The effect of grain refinement on mechanical properties is due to the change in the distribution of second phase particles. Titanium (Ti) and Boron (B) have traditionally been used for grain refinement in aluminum alloys. When Ti is added to the alloy, it forms a TiAl3 compound with aluminum and creates heterogeneous nucleation points in liquid aluminum. Today, research is also being conducted on the use of new generation grain refiners. Niobium (Nb) - Boron (B) alloys are used as new generation grain refiners. The fact that the lattice structures of Al3Nb and NbB2 alloys are very close to Al3Ti and TiB2 alloys gives these alloys an advantage to be a grain refiner candidate. In the thesis study, grain refiners were added to AlSi alloy at different parameters, including conventional and new generation grain refiners. After the additions, microstructure, hardness, wear, tensile, yield and elongation properties of the non-added and added alloys were compared. In addition, liquid metal quality was evaluated by bifilm calculations.