Effects of Laser Shock Peening on Tribological Properties of Ti-based Amorphous Alloy
Bulk amorphous alloys are promising engineering materials owing to their increased hardness,high strength,good corrosion resistance,and wear resistance.They have a wide range of applications in biomedical,marine engineering,and aerospace fields;however,their poor room-temperature plasticity limits the improvement of their tribological properties.We used a copper-mold spray casting technique to prepare a titanium-based amorphous alloy(Ti32.85Zr30.21Cu9Ni5.28Be22.66)and investigate the enhancement of its tribological properties.Subsequently,laser-shock treatment was employed,utilizing pulse energies of 3 J,5 J,and 7 J;pulse widths of 15 ns;a repetition rate of 0.5 Hz;spot diameter of 3 mm;and lap rate of 50％.Our investigation delved into multiple facets to comprehensively understand the impact of laser shock peening on this alloy.First,we examined the mechanical properties of the alloy specimen after laser shock treatment by evaluating both the surface and cross-sectional hardness.Additionally,we conducted X-ray diffraction(XRD)tests to explore any changes in the amorphous structure of the samples before and after laser shock treatment.Moreover,our research extended to the study of corrosion resistance of the specimens.We utilized a Gamry 1010E electrochemical workstation to measure the electrode potential and polarization curves of the amorphous samples in a 3.5％NaCl solution under varying laser pulse energies.Subsequently,we used a CFT-1 multifunctional friction and wear testing machine in conjunction with a Gamry 1010E electrochemical workstation to assess the tribological properties of the specimens.Finally,we elucidated the wear mechanism of the specimens by closely observing the wear morphology using a JSM6360-type scanning electron microscope.Notably,our XRD analysis revealed no obvious difference between the Ti-based amorphous alloys before and after the laser shock treatment.Importantly,we found that laser shock peening significantly enhanced the hardness and surface roughness of the impacted surface,as well as the cross-sectional hardness of the titanium-based amorphous alloys.Furthermore,this effect became more pronounced with increasing laser pulse energy,although the surface roughness exhibited a nuanced trend of initially increasing and subsequently decreasing.Additionally,laser shock peening demonstrated a remarkable capacity to augment the corrosion resistance of the titanium-based amorphous alloys in a simulated seawater environment.The residual stress generated by this process effectively mitigated the corrosion rate,although the improved surface roughness only marginally increased it.For instance,specimens impacted with a 3 J pulse energy displayed slight residual compressive stress and notably higher corrosion rates compared to the cast samples.Conversely,under a 20 N load and 7 J pulse energy,the corrosion rate was reduced by approximately 47.2％compared to that of the cast sample.Moreover,laser shock treatment substantially reduced both the corrosion and wear rates in titanium-based amorphous alloys,and this reduction became more pronounced as the laser pulse energy increased.For instance,at a 10N load,the wear rate after a 7-J pulse energy impact decreased by approximately 47.3％compared to that of the cast sample.Notably,the friction factor of the titanium-based amorphous alloy exhibited minimal change.The main wear mechanism of Ti-based amorphous alloys is adhesive wear.Laser shock is beneficial for the re-passivation of titanium-based amorphous alloys,inhibits plastic deformation and adhesion tendency,and improves their tribological properties in corrosive environments.After laser shock,the corrosion and wear performance of titanium-based amorphous alloys are improved,which provides a theoretical basis for the future application of titanium-based amorphous alloys.
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