表面改性对医用钛合金疲劳性能影响的研究进展OA

Medical titanium alloys,particularly the ubiquitous Ti-6Al-4V and various low-modulus β-type alloys,have established themselves as the gold standard for load-bearing orthopedic and dental implants due to their exceptional biocompatibility,high specific strength,and superior corrosion resistance.Despite these intrinsic advantages,the long-term clinical reliability of titanium implants is frequently compromised by fatigue failure,a phenomenon responsible for a significant portion of late-stage clinical complications.In the complex physiological environment of the human body,these alloys are subject to multi-axial cyclic loading,high-cycle alternating stresses during locomotion,and fretting wear at modular interfaces.These mechanical factors do not act in isolation;but coupled with the corrosive nature of body fluids,where chloride ions,proteins,and pH fluctuations synergistically accelerate the initiation and propagation of fatigue cracks.Consequently,enhancing the fatigue resistance of titanium alloys through surface modification has emerged as a pivotal research frontier.However,a major bottleneck persists.Namely,surface treatments designed to improve bioactivity or wear resistance often inadvertently degrade the fatigue life of the substrate,creating a paradoxical challenge in balancing mechanical durability with biological functionality. This paper provides a comprehensive review of the latest research progress in surface modification techniques specifically tailored to regulate the fatigue performance of medical titanium alloys.While existing literature predominantly focuses on the friction,wear,and corrosion resistance of these materials,reviews dedicated specifically to the nuances of their fatigue performance remain scarce and fragmented.This study fills that gap by critically analyzing the interplay between surface integrity,which is characterized by residual stress,surface roughness,and microstructural evolution,and the resulting biological responses,including osseointegration,antibacterial efficacy,and cytocompatibility.The modification strategies are categorized into mechanical,physical,chemical/electrochemical,and composite methods. Mechanical surface modification techniques,such as Shot Peening(SP),Wet Shot Peening(WSP),Ultrasonic Shot Peening(USP),and Laser Shock Peening(LSP),are evaluated in depth.These methods primarily function by inducing a deep layer of Compressive Residual Stress(CRS)and generating gradient nanostructures in the subsurface.By reducing the effective stress intensity factor at the surface,these modifications significantly delay crack initiation and retard crack growth rates.However,the review highlights a critical trade-off:aggressive mechanical treatments can lead to excessive surface roughness and micro-scale defects,which serve as stress concentrators that may negate the benefits of the compressive stress field. Furthermore,the review scrutinizes chemical and electrochemical methods,such as Nitriding and Micro-Arc Oxidation(MAO).Although MAO is highly effective at producing porous,bioactive ceramic coatings that promote bone ingrowth and can be doped with antibacterial agents,it often leads to a substantial reduction in the fatigue limit.This degradation is attributed to the brittle nature of the thick oxide layers and the presence of discharge pores acting as crack precursors.Similarly,physical methods like Physical Vapor Deposition(PVD)enhance surface hardness but face challenges regarding coating-substrate adhesion under long-term cyclic loading. To address these limitations of single-step modifications,this paper emphasizes the emerging paradigm of Composite Surface Modification.By strategically combining mechanical pre-treatments with subsequent biochemical functionalization,it is possible to"reconstruct"the surface stress field.This synergistic approach allows for the retention of beneficial compressive stresses to inhibit fatigue while providing an optimized topography for biological fixation.The review concludes that future research should focus on the quantitative analysis of failure mechanisms under multi-field coupling(corrosion-fatigue)and the development of clinical-oriented composite modification protocols.Such advancements are essential for ensuring the ultra-long-term service reliability of next-generation medical titanium implants.