Characterization of Individual Microneedles Formed on Alloy Surfaces by Femtosecond Laser Ablation
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Cross-sectional microstructural analyses of micron/nano-sized structures (termed microneedles) formed by low and high fluence pulse laser ablation of AISI 4340 steel, Ti6Al4V, and Al 5754 alloy specimens were performed. Dependence of length scale and orientation of microneedle microstructures on energy absorptance during laser irradiation, heat transfer direction, absorptivity, and thermal conductivity of the material was established. Microneedle nucleation and growth process were explained based on penetration depths, redeposition of ablated material, and ablation rates.
KeywordsLaser Fluence Femtosecond Laser Ablation High Laser Fluence Fluence Regime Ti6Al4V Surface
The current investigation was financially supported by Focus: HOPE (Detroit, MI) through funds from the Office of Naval Research. The authors acknowledge Dr. Kai Sun, EMAL, University of Michigan, for his help with the characterizations.
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