Impact of UV, Vis, and IR Emission Wavelengths on Morphology and Corrosion of Laser-Textured Fe-20Mn Biodegradable Alloy

Biodegradable alloys are promising biomaterials for realizing temporary implantable devices. Surface properties have a significant impact on the degradability of such materials; therefore, their modification can open interesting opportunities for controlling the dissolution in biological environment. At an industrial level, ultra-short pulse laser sources are now available for promoting precise surface properties tuning; such lasers offer the opportunity of adjusting the radiation emission wavelength. The scope of the present work is to explore the use of different harmonics, representative of the ultraviolet (UV, 343 nm), visible (Vis, 515 nm) and near infrared (nIR, 1030 nm) fields, emitted by a femtosecond laser to apply a surface modification on FeMn sheets. In particular, the effect of different emission wavelength on surface morphology, its phase structure, and degradation behavior of Fe-20Mn biodegradable alloy processed by femtosecond laser texturing was investigated for the first time. The laser texturing process was found able to induce surface reversion of martensite into austenite, while the use of different wavelengths affected the surface morphology and, accordingly, the degradation behavior in pseudo-physiological conditions. The varying thermal cycles applied to the material, along with the resulting diverse surface morphologies, can provide new options for the fine-tuning of its surface performance.