Surface quality represents a critical challenge in additive manufacturing (AM), with surface roughness serving as a key parameter that influences this aspect. In the aerospace industry, the surface roughness of the aviation components is a very important parameter. In this study, a typical Al alloy, AlSi10Mg, was selected to study its surface roughness when using Laser Powder Bed Fusion (LPBF). Two Random Forest (RF) models were established to predict the upper surface roughness of printed samples based on laser power, laser scanning speed, and hatch distance. Through the study, it is found that a two-dimensional (2D) RF model is successful in predicting surface roughness values based on experimental data. The best and minimum surface roughness is 2.98 μm, which is the minimum known without remelting. More than two-thirds of the samples had a surface roughness of less than 7.7 μm. The maximum surface roughness is 11.28 μm. And the coefficient of determination (R²) of the model was 0.9, also suggesting that the surface roughness of 3D-printed Al alloys can be predicted using ML approaches such as the RF model. This study helps to understand the relationship between printing parameters and surface roughness and helps print components with better surface quality.

This work investigates the effects of various processing parameters (laser power, scanning speed, hatch distance and beam offset) on the resultant inclined up-facing surface roughness of AlSi10Mg alloys produced by laser powder bed fusion (LPBF). A two-step approach, orthogonal test followed by the Doehlert matrix design (DMD) test is used to efficiently optimize the up-facing surface and contour parameters. The former method aims to determine the significance of variables while the latter one facilitates a rapid optimization. The results show that the interaction and interdependency among the parameters are of great significance to the obtainable surface roughness. Using a rational design of experiments, the optimized up-facing surface roughness of Ra of 5.4 μm is achieved. This is attributed to the elimination of the laser partition track and the reduction in irregularities at the edges of the parts. This work demonstrates an effective approach of experimental processing parameter optimization to improve the surface finish of LPBF parts.

With the upgrade of additive manufacturing (AM) equipment, pure copper and various Cu-based alloys with almost full density have been successfully produced, maintaining their excellent thermal and electrical conductivity and good mechanical properties at high temperatures as well. In this paper, a model with a series of inclined surface structures was designed and fabricated to investigate the structural design on the formability of CuCrZr alloy produced by laser powder bed fusion (LPBF). The typical structure dimensions of the as-built samples were measured and compared with their corresponding dimensions and the inclined angle (α) and the relative angle (γ) between the inclined surface and recoating directions. The results demonstrate that the inclined structures with α < 50° were fabricated either with varying buckling deformation and powder adhesion or in failure for severe distortion. The differences (L_d) between the typical structure dimensions and their models increase with the decreasing of α. It has been observed that L_d reaches 1 mm when α is 20° and drastically reduces to around 200 μm when α is above 50°. When α < 50°, L_d is generally increasing with a rising γ value from 0° to 180°, significantly affecting the dimensional accuracy.

A CoCrNi-AlTi medium-entropy alloy was fabricated via laser powder bed fusion (L-PBF), and its microstructural evolution and mechanical response during aging at 500–900 °C for 1 h were systematically investigated. The as-built alloy exhibits a hierarchical microstructure consisting of elongated columnar grains and dislocation-rich cellular substructures, which is associated with an excellent strength–ductility combination (YS: 848 MPa, UTS: 1136 MPa, EF: 32.6%). Upon aging, a pronounced precipitation-hardening response is observed, with a peak hardness of 501 ± 7 HV and an ultimate tensile strength of 1429 MPa achieved at 800 °C. TEM and STEM-EDS analyses indicate that Ti preferentially segregates along dislocation networks and grain boundaries at early aging stages, promoting the heterogeneous nucleation of nanoscale Ni–Al–Ti–rich precipitates that effectively impede dislocation motion. At elevated aging temperatures, additional Cr-enriched regions with diffuse compositional partitioning are observed within the FCC matrix, occurring concurrently with the peak mechanical performance. Further aging at 900 °C leads to strength degradation, which is attributed to precipitate coarsening and recovery-induced dislocation annihilation. These results highlight the critical role of L-PBF-induced defect structures in governing precipitation behavior and the resulting strength–ductility trade-off during post-build heat treatment of CoCrNi-AlTi medium-entropy alloys.