Design,Preparation And Properties Study Of Gradient Structured Pure Ti And ZE41 Mg Alloy

With the development of medical technology,the use of implant materials to assist treatment has become more and more popular,which involves a large number of biomedical metal materials.Biomedical metal materials have the characteristics of good biocompatibility,excellent mechanical properties,and non-toxicity,making them the most widely used implant materials and degradable medical materials in clinical applications.Due to the particularity of human body temperature and body fluid corrosion environment,metal materials are gradually corroded and lose stability.Their corrosion products and wear micro-swarf will have adverse effects on biological organisms and even produce toxicity,which seriously restricts the service life and safety of metal materials.Therefore,further improving the mechanical properties of medical metal materials and controlling their corrosion properties have important research value and application prospects.TA2 pure titanium and ZE41 magnesium alloy are typical representatives of biomedical load-bearing non-degradable metal materials and biomedical biodegradable metal materials.This subject takes hot-forging TA2 pure titanium and rolling ZE41 magnesium alloy as the research objects,and uses the ultrasonic rolling method to prepare a gradient structure on the surface.Then use OM,SEM,TEM,HAADF-STEM and other methods to in-depth characterize the microstructure characteristics and evolution of the material.Study the improvement effect of the mechanical properties and corrosion properties of gradient structure materials,establish the internal relationship between microstructure and material properties,and clarify the microscopic mechanism of performance changes.The research results showed that the ultrasonic rolling technology produced a gradient structure on the surface of TA2 pure titanium and ZE41 magnesium alloy.The surface grains of the gradient structure TA2 reach 53.4 nm,and the thickness of the gradient nano-layer is 300 μm;the surface grains of the gradient structure ZE41 are refined to 161 nm,and the thickness of the gradient nano-layer reaches 900 μm.The thickness of the deformed layer of the two samples exceeds the thickness of the sample.The gradient structure induces a hardness gradient distribution along the thickness of the sample,and the maximum hardness of the two materials appears on the treated surface.Compared with the untreated sample,the maximum hardness of the gradient structure TA2 increased by 43.2%,and the gradient structure ZE41 increased by 100%.The gradient structure significantly improves the strong plastic balance performance of the two materials.Compared with the untreated sample,the yield strength of the gradient structure TA2 is increased by 35.5%,and the ultimate strength is increased by11.6%,while maintaining a good elongation.The strength and plasticity of the gradient structure ZE41 are simultaneously improved.The yield strength is increased by about1.9 times,the ultimate strength is increased by 1.6 times,and the elongation is increased by 60%.The enhanced plasticity of the gradient structure material comes from the strengthening of fine grains on the one hand,and the synergistic toughness and hardening effect of the gradient grain structure on the other hand.The corrosion results show that the corrosion resistance of the gradient structure TA2 in Hank’s solution is slightly improved.As the immersion time increases,its corrosion resistance tends to be consistent with that of the untreated sample.The corrosion resistance of gradient structure ZE41 in short-term immersion is worse than that of ascast samples;after long-term immersion,the corrosion resistance of the two tends to be the same.In general,ultrasonic rolling has little effect on the corrosion resistance of ZE4 magnesium alloy.The as-cast and rolled samples are prone to local corrosion,while the gradient structure ZE41 tends to be uniformly corroded.