FIB-SEM Investigation of Laser-Induced Periodic Surface Structures and Conical Surface Microstructures on D16T (AA2024-T4) Alloy

Abstract

The use of aluminum alloy AA2024-T4 (Russian designation D16T) in applications requiring a high strength-to-weight ratio and fatigue resistance such as aircraft fuselage often demands the control and modification of surface properties. A promising route to surface conditioning of Al alloys is laser treatment. In the present work, the formation of ripples and conical microstructures under scanning with femtosecond (fs) laser pulses was investigated. Laser treatment was performed using 250 fs pulses of a 1033 nm Yb:YAG laser. The fluence of the pulses varied from 5 to 33 J/cm2. The scanning was repeated from 1 to 5 times for different areas of the sample. Treated areas were evaluated using focused ion beam (FIB)- scanning electron microscopy (SEM) imaging and sectioning, energy-dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM), and confocal laser profilometry. The period of laser-induced periodic surface structures (LIPSS) and the average spacing of conical microstructures were deduced from SEM images by FFT. Unevenness of the treated areas was observed that is likely to have been caused by ablation debris. The structural and elemental changes of the material inside the conical microstructures was revealed by FIB-SEM and EDX. The underlying formation mechanisms of observed structures are discussed in this paper.

Analysis of anti-reflection mechanisms of the black aluminum alloy made by femtosecond laser processing

“…The anti-reflective structures' internal content was investigated using FIB (FEI Helios NanoLab G3) crosssectional cutting and EDS analysis [29]. A protective platinum layer with a thickness of 500 nm is deposited to protect the underlying materials from the focused Ga + ion beam milling.…”

Advanced Surface Enhancement

“…As a consequence, aligned ripples with sub-micron period may form, or conical microstructures may form upon further treatment that can be used to modify the frictional and wetting properties of the surface. In study [5], treated areas at the surface of AA2024-T4 aluminium alloy were evaluated using focused ion beam (FIB)-scanning electron microscopy (SEM) imaging and sectioning, energy-dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM), and confocal laser profilometry, to reveal the surface profiles and subsurface structure of the laser-treated surfaces.…”

Study of Micro/Nano Structuring and Mechanical Properties of KrF Excimer Laser Irradiated Al for Aerospace Industry and Surface Engineering Applications

“…Hierarchical structures can also be developed using lasers with many important properties, such as super hydrophilic/super hydrophobic effects, self-cleaning and anti-icing properties on laserirradiated metals [6][7][8]. Surface structuring has tremendous technological applications, such as in the field of industry [9], biomedical [10] and optical sciences by growing various coatings and micro/nanostructures that are efficient for light detection, reflection, data storage, field emission and desired tribological properties of surfaces [11,12]. Laser-induced structuring can also cause the enhancement in surface roughness and increased adhesion of irradiated target surface [13].…”