Mg-Zn-Zr-Ce生物材料组织与性能的研究
发布时间：2019-03-09 14:13
【摘要】：镁合金高的比强度、杰出的生物相容性与可降解的特征使其成为21世纪最有前景的医用金属材料。然而其差的抗腐蚀能力是制约其临床应用的最大障碍,是以如何提高镁合金的抗腐蚀能力成为镁合金生物材料研究的重点。Mg-Zn-Zr系属于低细胞毒性的镁合金系,为进一步提高其抗腐蚀能力,可添加适量的稀土元素Ce。本研究设计并制备了Mg-2Zn-0.4Zr-0.6Ce生物镁合金,通过热处理与热挤压工艺提高合金的力学性能与抗腐蚀能力,通过光学显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、浸泡测试、电化学测试和拉伸试验研究了固溶处理、时效处理、热挤压以及再结晶退火对合金组织与性能的影响。结果表明,铸态Mg-2Zn-0.4Zr-0.6Ce合金主要由α-Mg和(Mg,Zn)11Ce相组成。不同温度(430、440、450、460、470℃)固溶处理后合金的第二相逐渐溶解,晶粒长大,由于(Mg,Zn)11Ce相具有高的热稳定性,固溶处理后仍有未溶解的(Mg,Zn)11Ce相。由于微电偶数量的减少与组织均匀化,固溶处理后合金的腐蚀速率降低,且随固溶温度的升高,合金在模拟体液中(SBF)的腐蚀速率和自腐蚀电流密度Icorr先减小后增大,容抗弧半径先增大后减小,在450℃固溶处理后合金在SBF中的腐蚀速率与Icorr最低,此时腐蚀速率和Icorr分别为0.7483mm·a~(-1)和0.93μA·cm-2。将在450℃固溶处理后的合金于250℃时效不同时间(8、12、16、20、24h),固溶态合金在时效过程中合金中析出细小的(Mg,Zn)11Ce相,且随着时效时间的延长,第二相的数目逐渐增大。由于引入了更多的微电偶,时效后合金的腐蚀速率增大,随着时效时间的延长,合金在SBF中的腐蚀速率和Icorr逐渐增大,容抗弧半径减小。时效8 h后合金的腐蚀速率和Icorr最小,此时腐蚀速率为0.8125 mm·a~(-1),Icorr为1.31μA·cm-2。由于弥散强化作用,时效后合金的抗拉强度得到提高。随着时效时间的延长,抗拉强度逐渐增大,伸长率减小。时效24 h后抗拉强度达到最大值,为209.4 MPa。从抗腐蚀能力的角度考虑,在250℃时效12 h后合金的综合性能最好,此时合金的抗拉强度为186.3 MPa,伸长率为12.3%,腐蚀速率为0.8573 mm·a~(-1)。将铸态Mg-2Zn-0.4Zr-0.6Ce合金在不同温度下(470、480、490、500、510℃)挤压,合金在热挤压过程中发生动态再结晶,挤压后组织由细小的再结晶晶粒与未再结晶晶粒组成。随着挤压温度的升高,再结晶晶粒体积分数逐渐升高,晶粒尺寸变化不明显,合金在SBF中的腐蚀速率和Icorr先减小后增大,容抗弧半径先增大后减小。490℃挤压后合金的抗腐蚀能力最好,腐蚀速率为0.9337 mm·a~(-1),Icorr为4.67μA·cm-2。因为细晶强化与位错强化作用,挤压后合金的抗拉强度得到提高。随着挤压温度的升高,抗拉强度先增大后减小,伸长率先增大后减小。490℃挤压后合金的综合力学性能最好,抗拉强度与伸长率分别为259.1 MPa、14.1%。将在490℃挤压的合金于不同温度下(150、200、250、300℃)再结晶退火3h。合金在再结晶退火过程中合金发生再结晶,未再结晶晶粒消失,随后晶粒逐渐长大。由于再结晶与位错密度的降低,退火后合金抗腐蚀能力得到提高,随着退火温度的升高,合金在SBF中的腐蚀速率和Icorr先减小后增大,容抗弧半径先增大后减小,合金的抗拉强度逐渐降低,伸长率先增大后减小。当退火温度高于200℃时,合金的自腐蚀电流密度(Icorr)与平均晶粒尺寸(d)满足Icorr=a+bd-1/2方程。综合考虑镁合金生物材料的抗腐蚀能力与力学性能,在200℃退火3 h后合金的Icorr最低,合金的综合性能最好,抗拉强度与伸长率分别达到245.8 MPa和16.2%,腐蚀速率为0.7235 mm·a~(-1)。
[Abstract]:The high specific strength, outstanding biocompatibility and degradability of the magnesium alloy make it the most promising medical metal material in the 21st century. However, the poor anti-corrosion ability is the biggest obstacle to the clinical application of the magnesium alloy, and it is the focus of the research on how to improve the corrosion resistance of the magnesium alloy. Mg-Zn-Zr is a low-cell-toxic magnesium alloy system, and a proper amount of rare-earth element Ce can be added to further improve the corrosion resistance of the magnesium alloy. The Mg-2Zn-0.4Zr-0.6Ce biological magnesium alloy was designed and prepared in this study. The mechanical properties and corrosion resistance of the alloy were improved by heat treatment and hot extrusion. The mechanical properties and corrosion resistance of the alloy were improved by means of an optical microscope (OM), a scanning electron microscope (SEM), a transmission electron microscope (TEM), and a soaking test. The effect of solution treatment, aging treatment, hot extrusion and recrystallization annealing on the microstructure and properties of the alloy was studied by electrochemical test and tensile test. The results show that as-cast Mg-2Zn-0.4Zr-0.6Ce alloy is mainly composed of 1-Mg and (Mg, Zn) 11Ce. The second phase of the alloy is gradually dissolved after solution treatment at different temperatures (430,440,450,460,470 鈩，
本文编号：2437536
[Abstract]:The high specific strength, outstanding biocompatibility and degradability of the magnesium alloy make it the most promising medical metal material in the 21st century. However, the poor anti-corrosion ability is the biggest obstacle to the clinical application of the magnesium alloy, and it is the focus of the research on how to improve the corrosion resistance of the magnesium alloy. Mg-Zn-Zr is a low-cell-toxic magnesium alloy system, and a proper amount of rare-earth element Ce can be added to further improve the corrosion resistance of the magnesium alloy. The Mg-2Zn-0.4Zr-0.6Ce biological magnesium alloy was designed and prepared in this study. The mechanical properties and corrosion resistance of the alloy were improved by heat treatment and hot extrusion. The mechanical properties and corrosion resistance of the alloy were improved by means of an optical microscope (OM), a scanning electron microscope (SEM), a transmission electron microscope (TEM), and a soaking test. The effect of solution treatment, aging treatment, hot extrusion and recrystallization annealing on the microstructure and properties of the alloy was studied by electrochemical test and tensile test. The results show that as-cast Mg-2Zn-0.4Zr-0.6Ce alloy is mainly composed of 1-Mg and (Mg, Zn) 11Ce. The second phase of the alloy is gradually dissolved after solution treatment at different temperatures (430,440,450,460,470 鈩，
本文编号：2437536
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