Tailoring multiscale microstructures for balanced mechanical and thermal performance of difficult-to-process pure Al parts produced by laser powder bed fusion additive manufacturing

Abstract

Thermal management components usually require complex structures with a balance of mechanical and thermal performance. Laser powder bed fusion (LPBF) is a promising additive manufacturing technique for fabricating complex heat-dissipation structural components. However, pure aluminum has important application prospects in the field of heat dissipation, but its lower melting point and laser absorption rate compared to alloys result in difficult processing characteristics during LPBF, which remains poorly understood. This work systematically investigated the influence of laser processing on the multi-scale microstructural features and the synergistic effect on the mechanical and thermal performance of LPBF-fabricated pure Al parts. Results revealed that increasing the scanning speed from 0.6 m/s to 1.2 m/s leads to refined grains, increased dislocation density, decreased maximum orientation density along < 001 > direction, and a higher fraction of high-angle grain boundaries. These microstructural changes, coupled with the evolving porosity content, result in an initial enhancement followed by a decline in both the ultimate tensile strength and elongation of the fabricated parts. The thermal conductivity gradually decreases with the increase of scanning speed, which is due to the increased grain boundaries, dislocations, and stress that enhance the scattering behavior of electrons and phonons. The established processing-microstructure-property relationships provide critical insights for developing LPBF-processed Al based materials with an optimal balance between mechanical and thermal performance, enabling their widespread applications in structural and thermal management components.