Investigation of AlCu20Si10Mg Alloy Fabricated by Laser Powder Bed Fusion in Additive Manufacturing

The production of metal components by Additive Manufacturing (AM) processes has been experiencing exponential growth in recent years. However, only a limited number of alloys can be processed through metal AM. To address this limitation, this thesis investigates optimization of process parameters in Laser Powder Bed Fusion (LPBF) – AM for an AlSi10Mg alloy with 20% wt. (Cu) aiming to significantly reduce defects such as porosity and cracks. LPBF parameters including laser power, scanning speed, and layer thickness were taken into account to assess their impact on the structural integrity of the fabricated samples. The research began with the fabrication of 15 cubic 10mm3 samples using gas atomised AlCu20Si10Mg powder. Microstructural analysis was conducted using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM) which assessed the porosity, melt-pool boundary and the dendritic structure of the samples. This analysis identified the optimal conditions that can contribute to reduced porosity and completely eliminated visible cracks, indicating enhanced structural integrity. Further investigations were conducted using X-Ray Diffraction (XRD) to identify the crystalline phases formed during the LPBF process. Major phases found in AlCu20Si10Mg includes 𝐴𝑙2𝐶𝑢 (θ) & α-Al which helps in alloy’s strengthening and hardness. Understanding the interactions among the alloy’s elements which are aluminum, copper, silicon, and magnesium, was crucial for refining processing conditions to further optimize the alloy’s microstructure. Lastly, Differential Scanning Calorimetry (DSC) provided insights about the thermal properties of the AlCu20Si10Mg alloy i.e. exothermic and endothermic reactions responsible for phase dissolution, precipitation and thermal stability to guide adjustments in heat treatment aimed at reducing defects. The findings of this research highlight the importance of precise control over LPBF parameters and detailed characterization of the developed alloy through SEM, XRD, and DSC analyses to minimize the common defects in additive manufacturing. Strategic modifications to LPBF parameters and an in-depth understanding of material behaviour have proven effective in mitigating issues like porosity and cracks in the AlCu20Si10Mg alloy, advancing its suitability for applications demanding high-quality, defect-free materials. This research contributes valuable insights to the broader field of AM processes, emphasizing the potential for industrial applications of optimized LPBF techniques.