Mg-xZr-ySr-zSn-0.5Ca生物镁合金组织，力学性能和腐蚀行为研究

发布时间：2018-03-24 03:31

  本文选题：生物镁合金　切入点：力学性能　出处：《江西理工大学》2017年硕士论文

【摘要】：生物镁合金作为新一代人体植入材料近年来备受全球研究者的关注。研究发现,将镁合金植入人体内,镁合金会自然降解,以此避免二次手术对人体造成的伤害和费用,另外自然降解产生的镁离子既无毒副作用和刺激性,在人体也无排斥和不良现象。相反还会参于人体新陈代谢,多余的镁离子会被排除体外。相比已经广泛应用于临床的钛合金,316L不锈钢、钴铬基合金等,生物镁合金具有生物安全性、可降解性以及与人体最接近的密度和弹性模量等优点,但镁合金的易被腐蚀和力学性能不高,一直是阻碍其广泛应用的关键问题。本论文的研究工作主要是以合金化为主,加入Sr、Zr、Sn、Ca等元素,再对合金进行轧制,挤压,热处理等工艺,改善生物镁合金的力学性能和耐腐蚀性能,主要的结论如下:1、轧制态镁合金主要包括α-Mg为基体,偏析的富Zr区以及Mg17Sr2,CaMgSn等组成。Zr、Sr、Ca、Sn等元素都能细化组织提高耐腐蚀性能和力学性能,但研究发现,根据Mg-Zr二元相图,Zr在液态镁中最大的固溶度为0.6%,虽然由于Ca元素的添加对增加Zr的固溶度有积极意义但结合本次实验结果,Zr的添加不宜大于1%,同样Sr含量对合金的性能呈现先增后减的现象,结合5组镁合金的组织性能分析合金元素Sr的加入量控制在1.5-3 wt.%之间比较合适。2、耐腐蚀性能的强弱是由晶粒尺寸和第二相的含量以及分布共同决定的。合金5(Mg-1.5Sr-0.5Sn-0.5Ca)的晶粒尺寸不是最小的,耐腐蚀性能却是最优(其中alloy5合金的抗拉强度为180Mpa,抗压强度能达到340Mpa,析氢腐蚀速率为0.68 ml/(cm2 day))。因此,探究镁合金中第二相分布规律和机理对镁合金的性能的提高有积极意义。3、挤压加工后获得的宏观组织结构和轧制加工有些类似,并且在均匀化退火后组织变得更加均匀。当保温温度确定时,保温时间是影响组织的重要因素之一,挤压后对Mg-xSr-yZr-z Sn-0.5Ca进行均匀化退火,当温度为450℃时,保温时间不宜超过12小时。4、镁合金的腐蚀一般以局部腐蚀(特别是点蚀)和晶界腐蚀为主,alloy1的SEM可以看到,在富Zr的晶界处附近,有被腐蚀留下的孔隙,由塔菲尔曲线拟合得知alloy1合金的腐蚀速率为3.29(mm/year),alloy1合金经过均匀化退火处理后的抗压强度提高了68%,达到510Mpa。
[Abstract]:Biomagnesium alloys, as a new generation of human body implant materials, have attracted worldwide attention in recent years. It has been found that magnesium alloys naturally degrade when magnesium alloys are implanted into human bodies, thereby avoiding the harm and cost of secondary surgery. In addition, the magnesium ions produced by natural degradation have neither toxic side effects nor irritation, no rejection or adverse phenomena in the human body. On the contrary, they are also involved in the metabolism of the human body. Superfluous magnesium ions will be excluded from the body. Compared with titanium alloy 316L stainless steel, cobalt-chromium base alloy and so on, biotic magnesium alloys have the advantages of biological safety, biodegradability, density and elastic modulus closest to human body, etc. However, the corrosion and mechanical properties of magnesium alloys are not high, which is the key problem that hinders their wide application. In this paper, alloying is the main research work, and then the alloy is rolled, extruded, heat treated and so on. To improve the mechanical properties and corrosion resistance of biological magnesium alloys, the main conclusions are as follows: (1) rolled magnesium alloys mainly include 伪 -Mg as matrix, Zr-rich segregation and mg _ (17) Sr _ (2) O ~ (2 +) CaMgSn, and other elements, such as .Zr17Sr _ (2) C _ (2) C _ (2) Ca _ (Sn) and so on, can refine the microstructure to improve the corrosion resistance and mechanical properties. But the study found that. According to the Mg-Zr binary phase diagram, the maximum solid solubility of Zr in liquid magnesium is 0.6. Although the addition of Ca has a positive effect on increasing the solubility of Zr, the addition of Zr should not be greater than 1 according to the results of this experiment. The performance of the system increases first and then decreases, Analysis of Microstructure and Properties of 5 groups of magnesium Alloys the addition of Sr in the range of 1.5-3 wt.% is suitable. The corrosion resistance is determined by the grain size and the content and distribution of the second phase. The alloy 5Mg-1.5Sr-0.5Sn-0.5Ca). The grain size is not the smallest. The corrosion resistance of alloy5 alloy is the best. The tensile strength, compressive strength and hydrogen evolution rate of alloy5 alloy are 180MPA, 340Mpaand 0.68 ml/(cm2, respectively. The investigation of the distribution law and mechanism of the second phase in magnesium alloy has positive significance for improving the properties of magnesium alloy. The macrostructure obtained by extrusion processing is similar to that obtained by rolling processing. When the holding temperature is determined, the holding time is one of the important factors affecting the microstructure. After extrusion, the Mg-xSr-yZr-z Sn-0.5Ca is homogenized and annealed at 450 鈩，

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