Ring beam shaping represents an innovative approach and a promising technique in Laser Powder Bed Fusion of metals (L-PBF/M). Due to its energy density distribution, it is capable to produce wider melt tracks, reducing the thermal gradients and enhancing process stability compared to traditional Gaussian beams.

This study aims to evaluate the effectiveness of using a ring-beam shape in L-PBF/M fabrication of Ti-6Al-4V components, by investigating its impact on temperature distribution, microstructural characteristics and residual stresses. Specifically, a coaxial dual-wavelength pyrometer has been employed to capture temperature data during fabrication, generating a heatmap of the process, while residual stress measurements have been conducted using the contour method and X-ray diffraction. The cooling rates have been also evaluated and correlated to the microstructural features and residual stresses.

Laser Powder Bed Fusion (L-PBF) enables precise fabrication of complex metal parts but is limited by slow build rates. Increasing laser power can help, but conventional Gaussian beams at high power cause excessive evaporation and spattering, leading to defects.

Defocusing reduces peak intensity but is limited by Rayleigh length and thermo-optical effects. Beam shaping offers a more effective solution, achievable through dual-core lasers or external optics like Multi-Plane Light Conversion (MPLC) technology, which enables adaptable beam profiles such as annular or M-shaped distributions.

This study applies beam shaping to high-power laser printing of nickel alloy 625, achieving a 3.3× speed increase while maintaining part quality. Mechanical testing, high-speed imaging, and particle tracing confirm the benefits of shaped beams over standard Gaussian profiles.

We will also discuss latest implementation including fast switch in between a shaped beam and the initial Gaussian.

Powder Bed Fusion of Metals with Laser Beam (PBF-LB/M) offers considerable potential for the fabrication of performance-enhancing soft magnetic components with high topology freedom for electrical machines. FeSi6.5 soft magnetic iron-silicon alloy is a pivotal component in multi-material soft magnets, owing to its high electrical resistivity and low magnetic losses. However, the high silicon content of 6.5 wt.% leads to inherent material brittleness, which presents several PBF-LB/M challenges. Rapid melting and solidification generate steep thermal gradients that cause significant stresses and associated cracks in the less ductile FeSi6.5 material. This effect is exacerbated in the case of a Gaussian energy distribution with extremely high local temperatures in the laser beam center. In this work, laser beam shaping with ring-core energy distribution for PBF-LB/M of FeSi6.5 to suppress cracking without additional heating is investigated. Correlations between Gaussian and ring-core energy distribution and their effect on component properties are analyzed and discussed.

Permanent magnets are essential in electric power generation, electromobility, and robotics applications. However, the high cost and limited availability of the required rare-earth (RE) elements pose a significant challenge. Therefore, laser powder bed fusion (PBF-LB) as a method to produce permanent magnets with near-net shapes provides new possibilities to optimize RE material consumption. However, a common limit of PBF-LB is the low coercivity of as-built parts, which arises from microstructural defects such as grain growth, oxidation, and poor alignment of magnetic domains caused by processing. To overcome this, we investigated the combined effects of process parameters and the surface modification with nanoparticles of Nd-Fe-B-based micropower feedstocks. Our results demonstrate that nanoparticles enhance solidification, leading to increased part density and coercivity. These findings provide valuable insights into optimizing rare-earth-based feedstocks for PBF-LB, enabling more sustainable and efficient production of high-performance permanent magnets.

THz metamaterials offer opportunities to address the "THz gap" caused by the weak electromagnetic response of natural materials in this frequency range. We present a novel design of three-dimensional, metallic "cactus-like" meta-atoms that exhibit electromagnetically induced transparency (EIT) and enhanced refractive index sensitivity at low THz frequencies (1).

The fabrication process combines multiphoton polymerization with selective electroless silver plating to create conductive and mechanically intact structures. Multiphoton polymerization enables the production of intricate, sub-micron features, while selective silver plating ensures the required metallic properties for THz interactions.

Experimental characterization using THz time-domain spectroscopy (THz-TDS) confirm the metamaterial’s response. This manufacturing approach shows the potential of these structures for slow light and high-performance sensing applications.

(1) Papamakarios, S. et al. Cactus-like Metamaterial Structures for Electromagnetically Induced Transparency at THz frequencies. ACS Photonics (2024). https://doi.org:10.1021/acsphotonics.4c01179