近β型医用钛合金形变织构演变规律及晶界特性研究

Improving the biomedical and mechanics compatibility and the safety for implanting are the currently and forward permanent research subject to biomedical titanium alloy. The TLM alloy, with a nominal chemical composition of Ti-3Zr-2Sn-3Mo-25Nb (wt.%), is a near β type biomedical titanium alloy independently designed and developed by Northwest Institute for Nonferrous Metal Research in China. It possesses lower elastic modulus (E) values, excellent strength and toughness，better wear resistance and fatigue that offers a good combination of the safety and quality for implanting. Intensive investigations have been focused on this TLM alloy regarding such scientific aspects that processing route, microstructure transformation and biocompatibility of micro-arc oxidation film on titanium alloy surface, etc. However, the texture developed and the character distribution of grain boundary under the condition of deformation to the biomedical titanium TLM have not yet been studied so far. However, the study of the evolution of the deformation texture TLM titanium alloy and the character distribution of grain boundary is important to understanding the deformation character and mechanism of the near β type biomedical titanium alloy and optimizing effectively processing technology through Meanwhile, it is important significance to improving the biomedical and mechanics compatibility and the safety for implanting of near β type biomedical titanium alloy. The present study was carried out to clarify evolution of the deformation texture TLM titanium alloy and the character distribution of grain boundary of TLM alloy, aiming at improving the mechanical properities for biomedical applications.

生物医用钛合金材料当前和今后面临的永久研究课题是如何改进和提高其生物相容性、力学相容性和植人物安全性问题。西北有色金属研究院自主设计和研发了一种新型近β型生物医用钛合金TLM(名义成分Ti-3Zr-2Sn-3Mo-25Nb)，固溶时效处理后可达到较高强度、优良塑韧性和高疲劳极限的综合匹配。目前对于TLM钛合金集中于加工工艺、组织演变及合金表面微弧氧化涂层的生物相容性等方面，对于合金在变形条件下的力学行为特征、织构演变规律及其晶界特征分布还未深入研究。而弄清楚TLM合金的形变织构演变规律及晶界特性分布能从微观结构上了解近β型钛合金形变行为特征及机理，进而能有效优化加工工艺及控制显微组织演变，对于改善和提高近β型生物医用钛合金的生物相容性和力学相容性具有重要的意义。因此，本项目从TLM合金形变织构演变规律及晶界特性分布方向展开研究工作，旨在改善和提高近β型生物医用钛合金的生物相容性和力学性能。

TLM钛合金是一种新型近β型生物医用钛合金，具有较高强度、优良塑韧性和高疲劳极限的综合匹配，适用于制作人体骨科植入器械和介入类器械。目前对于该合金在变形条件下的力学行为特征、织构演变规律及其晶界特征分布还未见报道。而弄清楚TLM合金的形变织构演变规律及晶界特性分布能从微观结构上了解近β型钛合金形变行为特征及机理，进而能有效优化加工工艺及控制显微组织演变，对于改善和提高近β型生物医用钛合金的生物相容性和力学相容性具有重要的意义。本项目通过静态压缩、热模拟压缩、XRD宏观织构分析、EBSD微观织构分析等试验方法，研究了TLM钛合金冷变形行为及织构演变规律研究、热变形条件下形变行为及织构演变规律研究、不同形变量和应变速率条件下晶界特征分布及其演变机制，主要结论如下：. (1) TLM合金室温压缩整个过程形变机理主要涉及位错滑移和孪生，同时变形过程中存在应力诱发α"相变。随着形变量的增加，TLM合金β相形变织构强度发生不断变化，相比较原始织构强度，其形变织构强度呈现降低-升高-降低的演变规律。5%～10%压缩量形变阶段，TLM合金α"相织构类型发生了明显的变化，其<2 2 0>织构随着形变量的增加趋于分散弱化。. (2) TLM钛合金在不同形变温度(750～850℃)、不同应变速率(0.001～1s-1)、不同形变量(5%～50%)热压缩条件下的织构具有各自不同的特征：随着形变温度的升高，TLM合金织构强度呈现先升高再降低的演变规律；随着应变速率由0.001s−1升高至1s−1，TLM合金织构强度呈现逐步升高的演变规律；随着形变量的增加，形变织构强度呈现升高-降低-升高的演变规律。. (3) 基于不同形变条件下的小变形量室温压缩试验结果表明：相比较0.001s-1应变速率，1s-1应变速率、4.5%以下不同形变量条件下重位点阵晶界具有不同的演变规律。形变量在3%～4.5%范围内，随着形变量的增加，Σ11和Σ29特殊晶界数量明显增加，Σ3和Σ13特殊晶界数量明显减少，Σ39特殊晶界数量减少。