心血管支架用生物可降解Mg-0.4Zr-xZn-yMn镁合金的组织及性能研究

发布时间：2018-01-20 11:53

本文关键词： 镁合金显微组织力学性能腐蚀性能热挤压　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：镁是人体必需的微量元素,而且具有良好的生物相容性,无毒无害并能在人体内降解无需二次手术等诸多天然优势,因此镁合金具备成为生物植入材料的潜力。另外近年来,由于新合金新工艺的引入,镁合金的力学性能和耐腐蚀性能得到了进一步提高,使镁合金在生物植入材料方面的应用成为可能。本文的研究目的是为开发一种应用于血管支架的生物镁合金材料,这种血管支架材料具有良好的力学性能以及耐腐蚀性能。本文研究选取了具有良好生物相容性,能够细化晶粒,并提高合金力学性能及耐腐蚀性能的Zn,Zr和Mn元素作为合金化元素,设计并制备了Mg-Zr-Zn-Mn系生物镁合金。分别研究Mn,Zn元素含量对Mg-Zr-Zn-Mn系合金的显微组织、力学性能和耐腐蚀性能的影响,从而找出最优的Mn和Zn元素含量,使其具有优良的综合性能。最后对综合性能最好的合金在不同挤压温度下进行热挤压加工,研究分析热挤压处理对合金的组织和性能的影响,并确定最佳的挤压温度。研究结果如下:通过分别加入Mn,Zn元素以及进行热挤压加工处理,镁合金的显微组织、力学性能和耐腐蚀性能均得到了显著改善。(1)Mn元素对铸态合金的显微组织和力学性能的影响:在mg-0.4zr-4zn合金中添加mn元素后,可以细化镁合金晶粒,有利于提高合金力学性能。由于mn元素在合金中不形成化合物,合金主要由镁基体,mg0.97zn0.03相和mn颗粒相组成,随着mn元素含量的增加,合金中一部分球状mg0.97zn0.03相转变为条状第二相并沿晶界分布,而mn颗粒相则较均匀地分布于基体中。mn元素含量为1.5wt.%时,合金的拉伸强度得到了显著提高,屈服强度为122mpa,抗拉强度为240mpa,伸长率为11.94%。(2)zn元素对铸态合金的显微组织和力学性能的影响:在mg-0.4zr-1.5mn合金中添加zn元素后,可以消除mn偏析并使mn颗粒相更加均匀分布,能够显著细化镁合金晶粒,并且随着zn元素含量的增加,合金的晶粒进一步细化,另外合金中mg0.97zn0.03数量也逐渐增加,当zn含量为2wt.%时,合金的伸长率达到最大,伸长率为14.42%。随着zn含量的进一步增加,合金晶粒尺寸也随之降低,基体中mg0.97zn0.03增多,从而有助于合金的屈服强度和抗拉强度提高,但伸长率降低。当合金中zn含量增加至5wt.%时,合金中条状mg0.97zn0.03则显著增多,不利于合金力学性能的提高。当zn含量为4wt.%时,合金的屈服强度和抗拉强度达到最高值。(3)热挤压可以显著细化mg-0.4zr-4zn-1.5mn合金的晶粒,大大提高了合金的力学性能。挤压态合金的平均晶粒尺寸由铸态合金的163.9μm下降到约7μm左右,并且合金中mg0.97zn0.03相更加细小并弥散分布,有利于挤压态合金力学性能进一步提高。另外挤压温度对合金的力学性能也有较大影响,当挤压温度为300℃时,合金的力学性能最高,屈服强度为220MPa,抗拉强度为300MPa,伸长率为18.71%,随着挤压温度的升高,合金的力学性能逐渐降低。挤压前均匀化热处理可以使粗大的树枝晶和第二相溶于基体,可以提高合金的可挤性。(4)腐蚀实验结果表明:添加适量的Mn元素能提高镁合金的耐腐蚀性能,但当Mn元素含量超过1.5wt.%时,合金的耐腐蚀性能降低。Zn元素可以显著提高合金的耐腐蚀性能,当Zn含量为2wt.%时,合金拥有最好的耐腐蚀性能,然而随着Zn含量的增加,合金中Mg0.97Zn0.03增多,导致合金的耐腐蚀性能降低。热挤压能够显著提高Mg-0.4Zr-4Zn-1.5Mn合金的耐腐蚀性能,并且挤压温度为300℃时合金的耐腐蚀性能比挤压温度为330℃和350℃时合金的耐腐蚀性能强。
[Abstract]:Magnesium is an essential trace element, but also has good biocompatibility, non-toxic and degradation in the human body without surgery two times and many other natural advantages, so magnesium alloy has become the biomaterials potential. In recent years, due to the introduction of new technology and new alloy, the mechanical properties of magnesium alloy and resistance the corrosion performance has been further improved, the magnesium alloy can be used in biological implant materials. The purpose of this study is to develop a biological magnesium alloy material applied to the stent, the stent material has good mechanical properties and corrosion resistance. This study has good biocompatibility, can refine grain, and improve the mechanical properties and corrosion resistance of Zn, Zr and Mn elements as alloying elements, design and Mg-Zr-Zn-Mn bio magnesium alloy was prepared respectively research. The Mn and Zn content on Microstructure of Mg-Zr-Zn-Mn alloy, mechanical properties and corrosion resistance, so as to find out the Mn and Zn elements were optimal, which has excellent comprehensive performance. Finally, the comprehensive performance of the best alloy at different extrusion temperature of hot extrusion processing, analysis on the effect of hot extrusion microstructure and properties of the alloy, and to determine the best extrusion temperature. The results are as follows: by joining Mn, Zn elements and process of hot extrusion of magnesium alloy, microstructure, mechanical properties and corrosion resistance were significantly improved. (1) effects on Microstructure and mechanical cast alloy the performance of the Mn elements: the addition of Mn element in mg-0.4zr-4zn alloy, magnesium alloy can refine grain, improve the mechanical properties of the alloy. Because Mn elements do not form compounds in the alloy, alloy is mainly composed of magnesium base Body, mg0.97zn0.03 phase and Mn particle phase, with the increase of Mn content in the alloy part of spherical mg0.97zn0.03 phase into strips and the second phase along the grain boundary, while the Mn particles are uniformly distributed in the matrix of.Mn element content is 1.5wt.%, the tensile strength of the alloy has been significantly improved, 122mpa yield strength, tensile strength 240mpa, elongation of 11.94%. (2) influence on Microstructure and mechanical properties of Zn cast alloy elements: the addition of Zn element in mg-0.4zr-1.5mn alloy, can eliminate the segregation of Mn and Mn particles are more uniform distribution, can refine grains of magnesium alloy, and with increase of Zn content the alloy grains are further refined, the number of mg0.97zn0.03 in the alloy will increase gradually, when the Zn content is 2wt.%, the elongation of the alloy reaches the maximum elongation of 14.42%. with the content of Zn further Increase the grain size of the alloy decreases, mg0.97zn0.03 in the matrix increased, thereby improving the yield strength and tensile strength in alloys, but the elongation decreased. When the Zn content in the alloy increases to 5wt.%, the alloy strip mg0.97zn0.03 is significantly increased, is not conducive to improve the mechanical properties of the alloy. When the Zn content is 4wt.%. The yield strength of the alloy and the tensile strength reaches the maximum value. (3) the hot extrusion grain can greatly refine mg-0.4zr-4zn-1.5mn alloy, greatly improve the mechanical properties of the alloy. The average grain size of the extruded alloy made of cast alloy 163.9 m down to about 7 m, and mg0.97zn0.03 in the alloy phase is more fine and diffuse distribution, is conducive to further improve the mechanical properties of the extruded alloy extrusion temperature on the mechanical properties. The alloy was also affected, when the extrusion temperature is 300 degrees centigrade, the mechanical properties of the alloy High yield strength 220MPa, tensile strength 300MPa, elongation is 18.71%, with the increase of the extrusion temperature, the mechanical properties of the alloy decreases gradually. Homogenization heat treatment before extrusion can make coarse dendrite and the second phase dissolved in the matrix, can improve the alloy can be squeezed. (4) the experimental results show that the corrosion adding an appropriate amount of Mn element can improve the corrosion resistance of magnesium alloy, but when the Mn content exceeds 1.5wt.%, the corrosion resistance of alloy decreased.Zn element can significantly improve the corrosion resistance of the alloys, when the Zn content is 2wt.%, the alloy has good corrosion resistance, however, with the increase of Zn content, alloy Mg0.97Zn0.03 leads to increased, the corrosion resistance of alloy decreased. Hot extrusion can improve the corrosion resistance of Mg-0.4Zr-4Zn-1.5Mn alloy, and the extrusion temperature is 300 DEG C when the alloy corrosion resistance than the extrusion temperature is 330 DEG C The corrosion resistance of the alloy is strong at 350 C.

【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.22;R318.08

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