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Item type:Publication, Access status: with files , Systematic study of the interplay between laser beam shape, energy input, and hatch spacing in PBF-LB/M of Ti-6Al-4V: experiments and numerical modeling(Elsevier, 2026-07-17); ; ; ; Programmable laser beam shaping tailors the spatial irradiance distribution in laser powder bed fusion (PBF-LB/M), enabling control over melt-pool geometry and defect formation. However, the coupled effects of beam shape, hatch spacing (track overlap), and energy input on densification and microstructural development remain insufficiently understood. Accordingly, Ti-6Al-4V is studied using single-track experiments, cube builds, and 3D transient multiphysics simulations across three ring-type beam profiles ranging from relatively core-weighted to strongly ring-dominated. Single tracks spanning a power–speed matrix (linear energy density, P/v) quantified melt-pool width, depth, and molten area and mapped stability regimes (fragmentation, necking, stable) and transition thresholds with increasing energy input. Cube specimens mapped relative density versus beam mode, areal energy density AEDh = P/(v h) (J/mm2), hatch spacing h, and geometric ratios h/d (d: effective beam diameter) and W/h (W: melt-pool width). Near-full density (~99.9%) was achieved for all profiles at AEDh ≥ 2.8–3.0 J/mm2; relatively more core-weighted profiles reached this at lower AEDh, whereas ringdominated profiles required higher input to suppress lack-of-fusion. Density dropped when h/d≳1, while W/h≳ 1.2 preserved high density. Microstructure and Vickers microhardness (HV0.2) were assessed across AEDh. All conditions exhibited martensitic α′ microstructures, and microhardness remained ≈360–395 HV0.2, converging once near-full density was reached. Simulations showed that ring-dominated density loss arises from insufficient inter-track remelting depth (cusp formation) despite lateral overlap, requiring higher overlap ratios for full fusion. Thermal gradients (G) and solidification rates (R) placed all cases in the columnar growth regime; higher G/R in more core-weighted profiles is consistent with stronger grain continuity than the more refined ringdominated structures.Publicationtype: Journal Article9 17 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Porosity and elevated-temperature tensile response of PBF-LB/M Ti-6Al-4V across laser beam profiles mapped using a spot-size-aware energy metricLaser beam shaping in PBF-LB/M modifies the spatial laser energy distribution, affecting melt-pool evolution, defect formation, and mechanical response. Ti-6Al-4V was processed using Gaussian, core–ring, and ring-dominated beam profiles. Measured beam maps were used to determine the effective beam diameter in a modified energy metric (VEDM, J mm⁻² s⁻¹/²) for cross-mode comparison. Densification and pore characteristics were assessed in cubes and tensile specimens. Core–ring and ring-dominated profiles transitioned from lack-of-fusion defects at low input to near-full density at higher input, whereas Gaussian shifted toward keyhole-type porosity at the highest input. At VEDM = 332 J mm⁻² s⁻¹ /², the µCT-scanned tensile gauge regions showed lower relative density for Gaussian (∼98.6%) than for core–ring and ring-dominated conditions (∼99.8%). Tensile specimens produced with Gaussian and ring-dominated beams were tested at RT, 200 °C, and 400 °C. All conditions showed temperature-dependent softening. However, at high VEDM and 400 °C, the ring-dominated condition retained higher ductility (∼10%) than the Gaussian condition (∼7%), while maintaining a comparable peak stress. Fractography showed pore-assisted initiation in the Gaussian condition and ductile tearing with pronounced necking in the ring-dominated condition. Overall, elevated-temperature tensile performance was primarily associated with pore type and severity, while VED<inf>M</inf> provides a practical framework for cross-mode comparison.Publicationtype: Journal Article11 12 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Advancing laser powder bed fusion of metals via tailored laser beam shaping: a critical reviewLaser beam shaping is increasingly explored to enhance Laser Powder Bed Fusion of Metals (PBF-LB/M) by controlling the spatial energy distribution within the laser spot. While conventional Gaussian beams remain widely used in commercial systems, their concentrated energy input can promote steep thermal gradients and localized overheating, which may restrict process stability, productivity, and part quality. This review critically synthesizes recent progress in laser beam shaping for PBF-LB/M, with emphasis on work from 2020 to early 2026. Compared with earlier reviews that mainly focused on optical implementation or broader laser–material processing concepts, this review integrates beam-shape generation with melt-pool dynamics, defect formation, surface quality, microstructural evolution, mechanical response, productivity, and emerging shape-aware process descriptors. The discussion shows how profiles such as core–ring, ring-dominant, top-hat, and elliptical beams can broaden stable process windows, suppress spatter and keyhole porosity, and promote more uniform thermal histories, with implications for surface quality, mechanical isotropy, and build efficiency. Modeling and simulation studies are also summarized to clarify the coupled heat-fluid–solid interactions controlling melt-pool behavior, thermal gradients, and solidification kinetics. Furthermore, major implementation challenges such as optical integration, energy-delivery stability, process reproducibility, and the lack of standardized beam descriptors are summarized. The review concludes by outlining emerging research directions aimed at enabling practical, reliable, and industrial-scale adoption of beam-shaping technologies in additive manufacturing.Publicationtype: Review Article15 28 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Towards controlled processing of high-conductivity Cu alloy (CuCrZr) on Inconel (IN718) substrate through beam shaping and process control in PBF-LB/M(Elsevier, 2026-06-27); ; ; ; Multi-material components that combine high-temperature structural performance with high thermal conductivity are of growing interest for advanced engineering applications. Laser powder bed fusion of metals (PBF-LB/M) offers unique opportunities to fabricate such components with precise control over geometry and composition, but the early stages of multi-material deposition remain poorly understood. In particular, the influence of substrate properties and process variables on interface formation, intermixing control, and defect evolution has not been systematically studied, especially for challenging alloys like copper and nickel-based superalloys. In this work, single-track experiments are conducted to investigate the deposition of a CuCrZr alloy on an IN-718 substrate, targeting the reduction of interfacial intermixing while preserving bonding integrity. The effects of laser power, scan speed, and laser beam shaping on melt pool morphology, substrate remelting, and compositional control at the interface are evaluated. Ring-dominant beam profiles achieve higher Cu retention (up to 53.9 wt% for Mode 3 and 47.5 wt% for Mode 6, versus 39.7 wt% for Gaussian), suppress keyhole formation, and substantially reduce the heat-affected zone width from 45 to 115 µm for Gaussian sources down to below 20 µm for Mode 6, which additionally decouples HAZ extent from process parameters. Liquation cracking at the HAZ, associated with Laves phase along Nb-enriched grain boundaries, was observed exclusively under core-dominant, high energy density conditions. Single-track experiments were deliberately selected as they represent the earliest and most substrate-dominated deposition stage, where thermal gradients are steepest and substrate-driven cracking mechanisms are most directly isolated. These results establish a mechanistic framework for understanding early-stage multi-material deposition, informing process parameter design in more complex geometries and guiding future studies aimed at controlling interfacial intermixing, minimizing defects, and improving the reliability of multi-material additive manufacturing.Publicationtype: Journal Article38 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Role of laser beam shape and energy density in modulating surface quality, porosity, microstructure, and mechanical properties of PBF-LB/M Ti-6Al-4V(Elsevier, 2026-01-03); ; ; ; Beam shaping has recently gained attention as a means to mitigate the thermal gradients and melt-pool instabilities associated with conventional Gaussian beams in laser powder bed fusion (PBF-LB/M), which often lead to surface roughness, defects, and microstructural inconsistency. This study examines the effects of different beam shapes and volumetric energy densities (VEDs) on the surface quality, porosity, microstructure, and mechanical response of Ti-6Al-4V. Cubic specimens were fabricated on an Aconity MIDI+ system using Gaussian, core-ring, and ring beam profiles over a VED range of 78–341 J/mm³. The results show that beam shaping with optimized VED reduces porosity, refines microstructure, and enhances mechanical performance. The Gaussian beam performed well at low VEDs (≤130 J/mm³) but exhibited increased surface roughness and keyhole porosity at higher energy inputs (≥150 J/mm³), whereas the ring-based beams initially showed higher porosity at low VEDs but achieved ∼99.97 % relative density and smoother surfaces at higher VEDs. The ring beam promoted stable conduction-mode melting, continuous prior-β grain growth, refined α′ martensitic microstructures, and strong crystallographic texture. From a mechanical perspective, Vickers hardness values (370–400 HV) correlated with the observed microstructural features. In addition, the Gaussian beam exhibited higher indicative strength at low VEDs but deteriorated with increasing energy input, whereas the ring beam showed the opposite trend, reaching an ultimate tensile strength of 1192 MPa and ∼21 % ductility under optimal conditions. Beam behavior was further evaluated using areal energy density (AED) normalized to the melt-pool width, indicating that melt-pool stability and the resulting surface quality, porosity, and microstructural evolution are primarily influenced by the spatial distribution of laser energy rather than nominal energy metrics alone. These findings provide a physical basis for laser beam shaping as an effective approach to broaden the stable processing window and achieve defect-free, texture-controlled Ti-6Al-4V components.Publicationtype: Journal Article17 28