發(fā)布時間：2018-03-03 03:16

  本文選題：醫(yī)用鎂合金　切入點：力學(xué)性能　出處：《哈爾濱工程大學(xué)》2016年博士論文　論文類型：學(xué)位論文

【摘要】：近年來隨著醫(yī)用鎂合金植入材料的需求增大,發(fā)展具有高的強(qiáng)韌性、優(yōu)異的抗腐蝕性和生物相容性的新型醫(yī)用鎂基合金具有重要的學(xué)術(shù)意義和應(yīng)用價值。本文中,首先設(shè)計制備了新型醫(yī)用Mg-3Sn-1Zn合金,系統(tǒng)地研究了不同擠壓變形工藝下Mg-3Sn-1Zn合金的的組織結(jié)構(gòu)和性能。之后在Mg-3Sn-1Zn合金的基礎(chǔ)上添加Mn元素,制備出Mg-3Sn-1Zn-0.5Mn合金,研究了其不同擠壓變形工藝下的微觀組織和性能,最后研究了Mg-3Sn-1Zn-0.5Mn合金的擠壓變形機(jī)理。Mg-3Sn-1Zn合金和Mg-3Sn-1Zn-0.5Mn合金的鑄態(tài)組織均由粗大不均勻的樹枝晶組成,顆粒狀的Mg2Sn相在樹枝晶間分布,層片狀的Mg2Sn相沿著晶界分布。固溶之后合金組織由粗大的等軸晶組成,Mg2Sn相完全融入到合金基體中,材料的綜合性能提高。Mg-3Sn-1Zn合金和Mg-3Sn-1Zn-0.5Mn合金在不同擠壓比(擠壓比8、16和25)下,擠壓溫度290℃時合金具有最好的綜合性能,組織形貌為細(xì)小的等軸晶,同時也有動態(tài)再結(jié)晶未完全的長條晶粒,力學(xué)性能優(yōu)異,耐腐蝕性能較好,溶血率最大為7.3%。擠壓溫度290℃時隨著擠壓比逐漸增大,合金性能微有降低;Mg-3Sn-1Zn合金在擠壓溫度為310℃-370℃時,金相組織均為等軸晶,Mg2Sn相在合金基體上均勻析出,隨著擠壓比的增大,晶粒尺寸增大,力學(xué)性能和耐蝕性有所降低。Mg-3Sn-1Zn-0.5Mn合金在擠壓溫度為310℃-370℃時,金相組織為等軸晶,隨著擠壓比的增大,晶粒尺寸降低,力學(xué)性能和耐蝕性增大。不同擠壓工藝下的Mg-3Sn-1Zn合金和Mg-3Sn-1Zn-0.5Mn合金的溶血率結(jié)果可知,這兩種合金擠壓變形后具有在血液環(huán)境應(yīng)用的可行性。Mn元素的添加使M g-3 Sn-1 Zn-0.5 Mn合金的性能優(yōu)于Mg-3Sn-1Zn合金的性能:力學(xué)性能方面,Mn元素加入可以細(xì)化Mg2Sn相,提高材料的力學(xué)性能。相同擠壓比下抗拉強(qiáng)度同比增加約10-20MPa,延伸率同比增加約2-6%:耐蝕性能方面,Mn元素加入會降低雜質(zhì)元素對鎂合金的不利影響,當(dāng)合金含有Zn元素時,添加Mn元素能明顯降低材料的腐蝕速度。相同擠壓比下自腐蝕電位由Mg-3Sn-1Zn合金的～-1.6V增加到Mg-3Sn-1Zn-0.5Mn合金～-1.5V,腐蝕電流速度同比減小約60%;溶血率方面,相同擠壓比下Mg-3 Sn-1 Zn-0.5Mn合金的溶血率低于Mg-3 Sn-1 Zn合金的溶血率。Mg-3Sn-1Zn-0.5Mn合金的組織演變特征為:1)變形量增加,晶粒尺寸呈現(xiàn)不斷減小的趨勢。2)Mg-3Sn-1Zn-0.5Mn合金在固溶無變形時,顆粒狀的Mn單質(zhì)沿著晶界分布,在擠壓變形后析出的Mg2Sn相均勻分布在合金基體上,Mg2Sn相的形狀為盤狀或桿狀。3)孿晶的數(shù)量隨著變形量的增加而減少。當(dāng)變形量較小時,擠壓變形使Mg-3Sn-1Zn-0.5Mn合金中固溶組織中的孿晶形態(tài)特征發(fā)生轉(zhuǎn)變,轉(zhuǎn)變后的孿晶可以發(fā)生退孿生現(xiàn)象,同時擠壓變形會產(chǎn)生新的孿晶,退孿生的孿晶和新生成的孿晶數(shù)量上相差不大,總體孿晶數(shù)量變化較小;當(dāng)變形量較大時,Mg-3Sn-1Zn-0.5Mn合金中發(fā)生退孿生現(xiàn)象的孿晶增加,同時較小的晶粒尺寸和較多的Mg2Sn相也抑制了變形引起的孿晶的生成,二者共同作用使孿晶數(shù)量急劇減少。Mg-3Sn-1Zn-0.5Mn合金變形機(jī)制以滑移和孿生為主,位錯運動和增殖會使位錯在變形過程中互相纏結(jié)、釘扎以及受晶界的阻礙而終止運動;孿生容易發(fā)生在不利于滑移的晶粒中促進(jìn)塑性變形,擠壓變形時變形生成的孿晶和退孿生同時發(fā)生。當(dāng)變形量較大時(擠壓比64),動態(tài)再結(jié)晶后較小的晶粒尺寸,使晶界滑動機(jī)制發(fā)揮了重要作用。固溶無變形和擠壓變形時,Mg-3Sn-1Zn-0.5Mn合金中的孿晶均為{1012}1011型孿晶,固溶無變形時Mg-3Sn-1Zn-0.5Mn合金中{1012}孿晶的長大機(jī)制為經(jīng)典的孿生位錯機(jī)制,{1012}孿晶界小角度偏離{1012}孿晶面;擠壓變形時Mg-3Sn-1Zn-0.5Mn合金中{1012}孿晶的長大機(jī)制為以擾動機(jī)制為基礎(chǔ),構(gòu)建的擾動為主,輔助剪切的模型,孿晶界面平直,{1012}界面并不在{1012}孿晶面上,且{1012}孿晶取向差也大角度的偏離了理論上的86.3°。
[Abstract]:In recent years, with the magnesium alloy implant materials increased demand, development has a strong toughness, has important academic significance and application value of new medical magnesium alloy compatibility of corrosion resistance and excellent biological. In this paper, the first design of a new type of medical Mg-3Sn-1Zn alloy prepared by different extrusion process of Mg-3Sn-1Zn alloy the structure and properties of the system. After the addition of Mn element on the basis of Mg-3Sn-1Zn alloy, prepared Mg-3Sn-1Zn-0.5Mn alloy, research the different extrusion deformation microstructure and performance process, the study of dendritic Mg-3Sn-1Zn-0.5Mn alloy extrusion deformation mechanism of.Mg-3Sn-1Zn alloy and Mg-3Sn-1Zn-0.5Mn alloy cast by coarse uneven, granular Mg2Sn phase in the interdendritic distribution, lamellar Mg2Sn phase with grain boundary distribution. After solution alloy group The fabric from coarse equiaxed crystal composed of Mg2Sn phase completely into the alloy matrix, improve the comprehensive performance of the material of.Mg-3Sn-1Zn alloy and Mg-3Sn-1Zn-0.5Mn alloy at different extrusion ratio (extrusion ratio 8,16 and 25), extrusion temperature of 290 DEG C when the alloy has the best overall performance, microstructure is fine equiaxed grains, and at the same time there is no dynamic recrystallization grain strip completely, excellent mechanical properties, corrosion resistance, the hemolysis rate of 7.3%. maximum extrusion temperature of 290 DEG C when the extrusion ratio increases, reduce the performance of the micro alloy; Mg-3Sn-1Zn alloy in the extrusion temperature is 310 DEG -370 DEG, microstructure are equiaxed crystal, phase in Mg2Sn alloy matrix with uniform precipitation, with the increase of the extrusion ratio, the grain size, mechanical properties and corrosion resistance of.Mg-3Sn-1Zn-0.5Mn alloy decreased in the extrusion temperature is 310 DEG -370 DEG, microstructure of equiaxed crystal, with the The increase of the extrusion ratio, the grain size decreased, the mechanical properties and corrosion resistance increases. The hemolysis of different extrusion process of Mg-3Sn-1Zn alloy and Mg-3Sn-1Zn-0.5Mn alloy rate results, these two kinds of alloy extruded with the performance of a M G-3 Sn-1 Zn-0.5 Mn alloy is better than that of Mg-3Sn-1Zn alloy in the feasibility of adding.Mn element of the application environment of blood the mechanical properties, the Mn element can refine the Mg2Sn phase, improve the mechanical properties of materials. The same extrusion ratio and tensile strength increased by approximately 10-20MPa, elongation increased by approximately 2-6%: corrosion resistance, Mn element will reduce the adverse effect of impurity elements on magnesium alloy, when the alloy contains elements of Zn, add Mn the element can significantly reduce the corrosion rate of the material. The same extrusion of Mg-3Sn-1Zn alloy by -1.5V ~ -1.6V to Mg-3Sn-1Zn-0.5Mn alloy to the corrosion potential, corrosion Corrosion current speed decreases about 60% compared to the same period; hemolysis rate, the same ratio of Mg-3 Sn-1 hemolysis hemolytic extrusion of Zn-0.5Mn alloy was lower than that of Mg-3 Sn-1 Zn alloy.Mg-3Sn-1Zn-0.5Mn alloy microstructure evolution rate: 1) increasing the amount of deformation, the grain size shows decreasing trend of.2) Mg-3Sn-1Zn-0.5Mn alloy in solution without deformation, granular the Mn element along the grain boundaries, the extrusion deformation of precipitated Mg2Sn uniformly distributed in the alloy, the Mg2Sn phase is in the shape of disc shaped or rod-shaped.3) twin number decreases with the increase of deformation. When the deformation is small, the extrusion deformation of Mg-3Sn-1Zn-0.5Mn immiscible alloy in twin tissue morphology the change of twins after the change can occur from twin phenomena, and extrusion deformation will produce new twin, the number of twin twin twin back and new generation of little difference on the overall. The number of twin small changes; when the deformation is large, the phenomenon of increasing twin twin annealing of Mg-3Sn-1Zn-0.5Mn alloy, while the smaller grain size and more Mg2Sn phase also inhibited formation of deformation twins, the two together to make a sharp reduction in the number of twin.Mg-3Sn-1Zn-0.5Mn alloy deformation mechanism by slip and twinning, and dislocation movement the proliferation of dislocation tangles each other in the deformation process, as well as by pinning grain boundaries hinder the termination of movement; twin to grain is not conducive to the promotion of sliding plastic deformation, the deformation of deformation twinning and twin formation retreat simultaneously. When large deformation (extrusion ratio 64), grain size after the dynamic recrystallization is smaller, so that the grain boundary sliding mechanism plays an important role. The solution without deformation and deformation, twinning in Mg-3Sn-1Zn-0.5Mn alloy are {1012}1011 Solid solution without deformation twinning and growth mechanism of Mg-3Sn-1Zn-0.5Mn alloy {1012} twin twin dislocation mechanism of classical {1012}, small angle offset {1012} twin twin boundary surface; extrusion deformation of Mg-3Sn-1Zn-0.5Mn alloy {1012} the twin growth mechanism with disturbance mechanism, construction disturbance, auxiliary shear model of the twin interface straight. The {1012} interface is not in the {1012} twin plane, {1012} and twin misorientation angles are deviated from the theory of 86.3 degrees.

【學(xué)位授予單位】：哈爾濱工程大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TG379

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