The efficiency of the fabrication and the cost of feedstock materials are important constraining factors for a wider application of the laser powder bed fusion (LPBF) process in the industry. Therefore, it is necessary to investigate the feasibility of using different particle size distributions (PSD) combined with higher layer thickness for achieving higher building efficiency and cost-effectiveness. This paper focuses on the effect of PSD (0–53, 15–53, 15–75, and 15–105 μm) on the print quality and mechanical properties of the LPBF-processed Ti-6Al-4V at a layer thickness of 60 μm. The results show that volumetric energy density (VED) range, which allows the coarse powder to reach full density, becomes relatively narrower but is still capable of producing fully dense parts when the parameters are properly adjusted. Among the fully dense specimens, the surface roughness varies slightly with the increase of VED and PSD. In the case of proper parameter selection, specimens made of coarse powder can still achieve low surface roughness. Only slight differences in mechanical performance are found for specimens produced using different PSD powders as they have almost identical microstructures. The issue of the anisotropic mechanical properties of the as-built specimens is resolved after annealing treatment at 800 °C for 2 h. This study provides a guideline for producing high-quality Ti-6Al-4V parts using a higher layer thickness and coarser powders.

This study investigates the influence of friction stir processing (FSP) on the microstructure, microhardness, and tribological properties of cold-sprayed AlSi10Mg+TiB₂ composite coatings on Al substrates. Due to the limitation of particle deformation during cold spraying, there were still some porosities and poorly bonded regions in the as-deposited AlSi10Mg+TiB₂ composite coating, which decreased the mechanical performance. Applying FSP to the composite coating significantly reduced the porosity and improved metallurgical bonding. Further, the FSP process induced severe plastic deformation, leading to a more uniform distribution of TiB₂ particles and a homogenized microstructure in the composite coating. The microhardness decreases progressively from the unaffected region through the heat-affected zone and thermomechanical-affected zone, and ultimately reaches its lowest value in the stir zone. The decreased microhardness is primarily attributed to the removal of the work-hardening effect. The FSP treatment seems to have little impact on the wear performance for both the pure AlSi10Mg and AlSi10Mg+TiB₂ composite samples, as the coefficient of friction values and wear rates remain essentially unchanged after the FSP treatments.