高能电脉冲对生物医用钛合金制备及性能影响的研究
发布时间：2018-08-21 11:23
【摘要】：钛合金TC4(Ti-6Al-4V)是目前应用最为广泛、最有前景的生物医用钛合金之一,如何提高其加工性能及其他理化性能以满足生物医用领域的需求,是亟待解决的关键技术问题。本文研究了高能电脉冲在钛合金TC4的加工处理及表面改性过程中的应用及其相关机理。首先,通过研究高能电脉冲处理冷加工钛合金TC4的局部再结晶过程发现,电脉冲处理后钛材的断裂伸长率平均提高113.5%,而钛材的强度几乎没有变化,同时力学性能的各向异性明显降低,微观组织由初始沿轧向分布的条状晶粒转变为没有明显取向性的等轴晶粒。接着,通过研究高能电脉冲处理冷加工钛合金TC4的完全再结晶和织构演变发现,电脉冲明显降低层片状加工孪晶的退化、非基面取向的再结晶晶粒生长和织构演变的表观温度,通过建立电脉冲过渡段上的热力学和动力学模型,发现当表观温度高于门槛值时(366℃)电脉冲的非热效应在完全再结晶和退孪晶过程中逐渐占据主导地位,该结论与实验结果比较吻合。然后,通过研究高能电脉冲处理热加工层片状组织钛合金TC4的相变球化过程发现,高能电脉冲能显著提升材料的塑性(132.4%),同时能促进热加工层片组织的相变过程β-Ti→α-Ti并形成细小的等轴化微观组织。另外,通过研究高能电脉冲在材料表面制备纳米氧化钛层的过程中,发现在表面形成的具有微波型氧化钛显微粗糙表面和类骨蜂窝状纳米孔结构的金红石型氧化钛层增强了材料的耐腐蚀性能和生物相容性,电脉冲的电磁场效应和热效应加快了氧化速率(较传统热表面氧化速率高两个数量级),降低了氧化层的厚度。最后,探索了电脉冲(辅助)加工制备高性能钛合金的工艺:高能电脉冲辅助超声冲击表面处理(电冲击)和高能电脉冲辅助轧制(电轧)过程。通过研究发现,电冲击能够通过动态再结晶和相变过程诱导纳米晶和β相的生成,同时加大了表面塑性流变的影响深度和程度,进一步增大了材料表面硬度和耐磨性;电轧工艺通过动态再结晶过程弱化进入轧辊前材料的基面织构、诱导晶粒方向横向偏转、增加中间取向差角晶界,从而降低加工温度和变形抗力,提高成材质量和综合力学性能。
[Abstract]:Titanium alloy TC4 (Ti-6Al-4V) is one of the most widely used and promising biomedical titanium alloys. How to improve its processing performance and other physical and chemical properties to meet the needs of biomedical field is a key technical problem to be solved urgently. In this paper, the application of high energy electric pulse in the process of processing and surface modification of titanium alloy TC4 and its related mechanism are studied. Firstly, by studying the local recrystallization process of cold working titanium alloy TC4 treated by high energy electric pulse, it is found that the average elongation at break of titanium is increased by 113.5%, but the strength of titanium is almost unchanged. At the same time, the anisotropy of mechanical properties was obviously decreased, and the microstructure changed from the initial stripe grain to the equiaxed grain with no obvious orientation. Then, by studying the complete recrystallization and texture evolution of TC4 treated by high energy electric pulse, it is found that the degradation of lamellar processing twins and the apparent temperature of recrystallization grain growth and texture evolution of non-base-oriented recrystallized titanium alloys are obviously reduced by electrical pulse. By establishing thermodynamic and kinetic models of electric pulse transition, it is found that the non-thermal effect of electric pulse (366 鈩，
本文编号：2195561
[Abstract]:Titanium alloy TC4 (Ti-6Al-4V) is one of the most widely used and promising biomedical titanium alloys. How to improve its processing performance and other physical and chemical properties to meet the needs of biomedical field is a key technical problem to be solved urgently. In this paper, the application of high energy electric pulse in the process of processing and surface modification of titanium alloy TC4 and its related mechanism are studied. Firstly, by studying the local recrystallization process of cold working titanium alloy TC4 treated by high energy electric pulse, it is found that the average elongation at break of titanium is increased by 113.5%, but the strength of titanium is almost unchanged. At the same time, the anisotropy of mechanical properties was obviously decreased, and the microstructure changed from the initial stripe grain to the equiaxed grain with no obvious orientation. Then, by studying the complete recrystallization and texture evolution of TC4 treated by high energy electric pulse, it is found that the degradation of lamellar processing twins and the apparent temperature of recrystallization grain growth and texture evolution of non-base-oriented recrystallized titanium alloys are obviously reduced by electrical pulse. By establishing thermodynamic and kinetic models of electric pulse transition, it is found that the non-thermal effect of electric pulse (366 鈩，
本文编号：2195561
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