Study On The Mechanical Property And In Vitro Degradation Behavior Of ZnMgY Alloy

Biodegradable metal materials play an important role in the medical field due to their good mechanical properties and biodegradability.At present,among the commonly used biodegradable metal materials,the corrosion rate of magnesium-based alloy is too high while the corrosion rate of iron-based alloy is too low.Zinc is considered as a promising new generation of biodegradable metal materials because of its moderate corrosion rate and good biocompatibility.However,the poor mechanical properties of pure zinc can not meet the clinical needs,the addition of alloying elements can effectively improve its mechanical properties.In this thesis,a new Zn-1Mg-1Y ternary zinc-based biodegradable alloy was prepared by introducing Mg and Y elements.The microstructure,mechanical properties and in vitro degradation behavior of the Zn-Mg-1Y alloy were studied by comparison with Pure Zn and Zn-1Mg alloy to lay the foundation for clinical application of ZnMgY alloys.The main research work and achievements completed in this paper are as follows:1.The Zn-1Mg-1Y alloy was prepared and heat treated,and its microstructure was analyzed.It is found that the Zn-1Mg-1Y alloy is consisted ofα-Zn phase,Mg₂Zn₁₁1 phase and Y₂Zn₁₇7 phase.Mg and Y elements can effectively refine grain.2.The mechanical properties of the alloy were analyzed by hardness test,tensile and compression test.It is found that the hardness ofα-Zn phase is the lowest,and theα-Zn/Mg₂Zn₁₁eutectic has a higher hardness,and the Y-rich phase has the highest hardness.Compared with pure Zn and Zn-1Mg alloy,Zn-1Mg-1Y alloy has the highest hardness and the highest compressive strength.Its ultimate tensile strength and elongation are much higher than that of pure Zn but slightly lower than that of Zn-1Mg alloy.3.The in vitro degradation behavior of Zn-1Mg-1Y alloy was studied by electrochemical test and immersion test.Electrochemical test results show that the corrosion resistance of Zn-1Mg-1Y alloy in simulated body fluid is between that of Pure Zn and Zn-1Mg alloy.The immersion test results show that Zn-1Mg-1Y alloy exhibits pitting corrosion behavior,and its corrosion rate is the highest under55-days immersion.In addition,Y element can significantly increase the Ca:P ratio of the material surface indicating the improvement of the biological activity.