Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore
doi:10.3850/978-981-18-6021-8_OR-17-0076
Microstructure refinement of cast high-Si Al alloy via laser remelting
1School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
2Singapore Institute of Manufacturing Technology, 73 Nanyang Drive, Singapore 637662, Singapore
ABSTRACT
High-Si Al alloys are suitable materials for thermal management applications such as electronic packaging because they possess low density, high thermal conductivity, low coefficient of thermal expansion and high specific strength. Casting is the cheapest and the most convenient method to fabricate high-Si Al alloys. However, the low solidification rate of the casting process leads to the formation of coarse primary Si and needle-shaped eutectic Si, which result in poor mechanical properties, impeding their applications. Laser remelting of the cast high-Si was attempted to refine the microstructures through rapid melting and solidification. There are large numbers of studies about laser remelting on low-Si Al alloys, but the information on high-Si Al alloys is limited. In this work, laser remelting was conducted on a cast high-Si Al alloy with 50 wt.% Si (Al-50Si) to achieve the microstructure refinement. Results show that the distribution of much finer primary Si particles was uniform in the matrix in the fully remelted region after the laser remelting. In addition, the laser remelting process was found to be effective in eliminating porosity in the as-cast microstructures. Microhardness of the laser remelted regions increased significantly due to the microstructural refinement.
Keywords: High-Si Al alloy, Casting, Laser remelting, Microstructure refinement
1School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
2Singapore Institute of Manufacturing Technology, 73 Nanyang Drive, Singapore 637662, Singapore
ABSTRACT
High-Si Al alloys are suitable materials for thermal management applications such as electronic packaging because they possess low density, high thermal conductivity, low coefficient of thermal expansion and high specific strength. Casting is the cheapest and the most convenient method to fabricate high-Si Al alloys. However, the low solidification rate of the casting process leads to the formation of coarse primary Si and needle-shaped eutectic Si, which result in poor mechanical properties, impeding their applications. Laser remelting of the cast high-Si was attempted to refine the microstructures through rapid melting and solidification. There are large numbers of studies about laser remelting on low-Si Al alloys, but the information on high-Si Al alloys is limited. In this work, laser remelting was conducted on a cast high-Si Al alloy with 50 wt.% Si (Al-50Si) to achieve the microstructure refinement. Results show that the distribution of much finer primary Si particles was uniform in the matrix in the fully remelted region after the laser remelting. In addition, the laser remelting process was found to be effective in eliminating porosity in the as-cast microstructures. Microhardness of the laser remelted regions increased significantly due to the microstructural refinement.
Keywords: High-Si Al alloy, Casting, Laser remelting, Microstructure refinement
