A model for solute evolution in laser powder bed fused Al-Si alloys and its application to improve thermal conductivity

Abstract

A model capable of describing the solute evolution in laser powder bed fused (LPBF) Al-Si alloys has been proposed. The proposed model incorporates the use of three-dimensional Rosenthal equation and a rapid dendrite growth theory. Due to the analytical nature of the equation and the theory, the avoidance of modeling detailed microstructure of cells/dendrites as well as the eutectic, and the neglect of grain nucleation/elimination process, the proposed model is efficient at calculating, taking merely ∼10 min for portraying the spatial distribution of dissolved solute in an entire melt pool. The model was validated by scanning transmission electron microscopic-energy disperse spectrum (STEM-EDS) analysis. The validated model was subsequently applied in designing fabrication strategy of LPBF Al-Si alloys, in hope of improving the alloys’ thermal conductivity through purposefully adjusting processing parameters. This objective was successfully achieved, based on the fact that among imperfections induced by LPBF, dissolved solute atoms are the dominant influencing factor for thermal conductivity, and that the model can reveal the correlations between the overall amount of dissolved solute in the solid solution matrix and laser/feedstock powder parameters.