TY - JOUR A1 - Porta-Velilla, L. A1 - Martínez, E. A1 - Frechilla, A. A1 - Castro, M. A1 - de la Fuente, G. F. A1 - Bonse, Jörn A1 - Angurel, L. A. T1 - Grain orientation, angle of incidence, and beam polarization effects on ultraviolet 300 ps-laser-induced nanostructures on 316L stainless steel N2 - Laser-induced periodic surface structures (LIPSS) represent a unique route for functionalizing materials through the fabrication of surface nanostructures. Commercial AISI 316L stainless steel (SS316L) surfaces are laser treated by ultraviolet 300 ps laser pulses in a laser line scanning (LLS) approach. Processing parameters are optimized (pulse energy of 2.08 µJ, pulse repetition frequency of 300 kHz, and suitable laser scan and sample displacement rates) for the generation of low spatial frequency LIPSS over a large 25 × 25 mm2 area. Different angles of incidence of the laser radiation (0°, 30°, and 45°) and different linear laser beam polarizations (s and p) produce a plethora of rippled surface morphologies at distinct grains. Scanning electron microscopy and 2D Fourier transforms, together with calculations of the optical energy deposited at the treated surfaces using Sipe's first-principles electromagnetic scattering theory, are used to study and analyze in detail these surface morphologies. Combined with electron backscattering diffraction, analyses allow associating site-selectively various laser-induced-surface morphologies with the underlying crystalline grain orientation. Resulting grain orientation maps reveal a strong impact of the grain crystallographic orientation on LIPSS formation and point toward possible strategies, like multi-step processes, for improving the manufacturing of LIPSS and their areal coverage of polycrystalline technical materials. KW - Laser-induced periodic surface structures (LIPSS) KW - Steel KW - Grain orientation KW - Electron backscattering diffraction (EBSD) KW - Laser processing PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-588929 DO - https://doi.org/10.1002/lpor.202300589 SN - 1863-8899 SP - 1 EP - 21 PB - Wiley-VCH GmbH CY - Weinheim AN - OPUS4-58892 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gräf, S. T1 - Ion marker implantation as key to understand the formation of femtosecond LIPSS on steel N2 - Ultrashort laser (fs-laser) pulses can be used to generate laser-induced periodic surface structures (LIPSS, ripples) on different types of materials. A variety of potential applications of these grating-like LIPSS have already been demonstrated in the field of surface functionalization. Examples include structural colours (e.g. for optical effects or safety features), beneficial friction and wear reduction, modification of the wetting behaviour of surfaces, and antibacterial or cell adhesion promoting properties for medical implants. Despite decades of research, however, some aspects regarding the formation mechanism are still unclear and the subject of controversial debate. This involves the two main models of coherent electromagnetic scattering and matter reorganization, which are used for explaining aspects of LIPSS formation and phenomenology. One major issue is to quantify the actual amount of material removal during the fs-laser processing due to the lack of an independent depth reference and to visualize the so-called heat-affected zone accompanying intense fs-laser irradiation. In the present study, near-surface implantation of Mn and N ions into different material depth of Mn-free austenitic stainless steel alloy FeCrNiMo18-12-2 was used to create reference layers of a defined thickness containing the respective elements. LIPSS (type low-spatial frequency LIPSS, LSFL) were fabricated on the polished substrate surfaces in an air environment by fs-laser irradiation (λ = 1025 nm, τ = 300 fs, frep = 100 kHz, F = 1.5 J/cm2). The implanted layers subsequently served as a kind of coordinate system to assess the material removal during the formation process via cross-sectional Transmission Electron Microscopy (TEM) and Energy Dispersive X-ray Spectroscopy (EDXS). Using both analysis methods enabled in particular to determine the position of peaks and valleys of the LIPSS topography in relation to the initial surface before fs-laser irradiation. This confirmed the selective ablation in the LIPSS valleys. Moreover, linking changes in the material’s microstructure, e.g., the crystallinity and near surface elemental composition before and after fs-laser treatment, gave additional insights regarding the transient cooling rates, as recently shown for NiTi alloys. T2 - 13th International LIPSS Workshop CY - Enschede, Netherlands DA - 29.10.2015 KW - Energy dispersive X-ray analysis (EDX) KW - Ion implantation KW - Laser-induced periodic surface structures (LIPSS) KW - Steel KW - Transmission electron microscopy (TEM) PY - 2025 AN - OPUS4-64900 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gräf, S. T1 - Ion marker implantation for tracing the formation of femtosecond LIPSS on steel N2 - An ion marker experiment is conducted to investigate the formation of low spatial frequency laser-induced periodic surface structures (LIPSS) on stainless steel surfaces upon scan-processing with femtosecond laser pulses (300 fs, 1025 nm, 100 kHz) focussed to a spot diameter of ~20 µm. Defined concentration depth profiles of 14N^+- and 55Mn^+-ions were implanted below the polished surface of a cast Mn- and Si-free stainless steel AISI 316L using an acceleration energy of 380 keV. This generated two distinct “depth-tracer-layers” ~135 nm (55Mn) and ~340 nm (14N) below the sample surface. The sample morphology and microstructure were evaluated before and after LIPSS-processing using scanning and transmission electron microscopy techniques in top-view and cross-sectional geometry. Energy-dispersive X-ray spectroscopy (EDXS) allowed to visualize the depth distribution of the marker elements, the steel constituents, and of oxygen involved through the laser processing in ambient air. These experiments revealed that the LIPSS on this metal are predominantly formed by material removal through locally varying ablation and, to a lesser extent, by local melt displacement effects prior to the re-solidification. Moreover, the processing in air leads to the formation of a less than 10 nm thick laser-induced oxide layer covering the steel surface. Our new tracer ion approach contributes to the ongoing debate on the relevance of electromagnetic or hydrodynamic effects during the formation of LIPSS. T2 - E-MRS Spring Meeting 2025 CY - Strasbourg, France DA - 26.05.2026 KW - Laser-induced periodic surface structures (LIPSS) KW - Steel KW - Ion implantation KW - Transmission electron microscopy (TEM) KW - Energy dispersive X-ray analysis (EDX) PY - 2025 AN - OPUS4-63274 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -