Study On The Functional Surface Properties Of Zr-Cu-Al Amorphous Alloys By Pulse Laser Microfabrication

The potential applications of bulk amorphous alloys as high-performance materials in the biomedical field have attracted increasing attention.Therefore,the critical dimensions,corrosion behavior,and biocompatibility of various amorphous alloys have been extensively studied to advance their applications in implants and medical devices.In the human in vivo environment,the main causes of artificial implant failure include,in addition to infection,aseptic loosening due to poor corrosion resistance of the material,low inlay with the bone tissue and poor osseointegration,which are importantly associated with the surface characteristics of the material.Pulsed lasers show unique charm in the preparation of biomimetic micro/nanostructures on the surface of biological materials,which can change the surface wettability,physicochemical properties,and biocompatibility of materials.In this paper,the Ni-free Zr-Cu-Al amorphous alloy is surface modified by two different pulses of nanosecond and femtosecond lasers to achieve improved corrosion resistance and bioactivity of the material in simulated body fluids.The study focuses on the following:The surface of Zr₄₇Cu₄₆Al₇amorphous alloy was micromachined using nanosecond short pulse laser and femtosecond ultrashort pulse laser respectively to test the surface microstructure under different laser parameters.In nanosecond laser processing,weaker ablation patterns are processed on the material surface at weaker laser power,and increasing the power or decreasing the speed,dense micron-sized small particles are prepared on the material surface.During femtosecond laser processing,at lower power and slower scanning speed,the processed surface is rounded and corrugated,increasing the laser power,the surface shape gradually changes to smooth grooves,and then increasing the scanning speed,the spot superposition rate decreases and the surface shape shows a fish scale shape,and finally transitions to a connected ablation pit shape.The roughness and wettability of the surface change significantly after pulsed laser processing.Crystals were generated on the surface of the specimen after nanosecond laser treatment,and the specimen remained amorphous after femtosecond laser treatment.The unprocessed specimens exhibited hydrophilic properties,and the surface roughness of the specimens was increased after nanosecond laser micromachining,and the surface water contact angle was drastically reduced.The surface roughness of the specimens also increased after femtosecond laser micromachining,and the overall roughness was slightly lower than that of the nanosecond laser processed specimens,but the surface wettability did not all decrease.Regardless of the femtosecond laser power,the surface water contact angle changes from hydrophilic to hydrophobic as the scanning speed increases from slow to fast,which is especially obvious at high power.Electrochemical corrosion evaluation was performed in a simulated physiological environment by electrochemical testing.The open circuit potential,impedance spectrum,and polarization curve data of the electrochemical corrosion test showed that the corrosion resistance of the specimens processed by different nanosecond lasers were all improved to different degrees.When the nanosecond laser power ranged from small to large and the scanning speed ranged from slow to fast,the corrosion resistance of the specimen showed signs of rising before declining,and the combination of moderate power and speed was the optimal parameter.The corrosion resistance of the specimens increased with the decrease of the scan spacing at different scan spacing,and the analysis concluded that the small spacing and the small percentage of unprocessed area reduced the chance of corrosion occurrence.The electrochemical corrosion results of the femtosecond laser-treated specimens showed that the corrosion resistance of the laser-treated samples was higher than that of the original samples,and the corrosion resistance of the ablated samples gradually increased with the increase of laser power.The biological activity of the samples after being immersed in artificial simulated body fluids was compared before and after laser processing.The unprocessed specimens were able to form small white hydroxyapatite（HA）particles on the surface after immersion in artificial simulated body fluids.After pulsed laser processing,the newly generated surface morphology was able to modulate the position of hydroxyapatite formation,with denser HA formation on the recast bumps at the spot edges and less formation in the spot center region,which also reflects the side effect that the reaction with simulated body fluid is reduced in the spot center region after pulsed laser processing,thus improving the corrosion resistance to varying degrees.The results of energy spectral surface scans showed that the HA content deposited on all surfaces after pulsed laser processing was not lower than the HA content deposited on unprocessed surfaces,and that pulsed laser processing improved the bioactivity of the material.Aiming at the problems of poor biocompatibility and corrosion resistance of amorphous alloy implants,this paper uses pulsed laser micromachining technology to modify the surface of amorphous alloys.The laser treatment improves the surface structure of the amorphous alloy,and the machined surface enhances the biological properties under the simulated human physiological environment.It provides a technical basis for improving the success rate of amorphous alloy implantation.Figure[39]table[14]reference[77]...