复相Ti-V-Al形状记忆合金的马氏体相变及力学行为

发布时间：2018-06-29 02:40

  本文选题：原位自生TiB+TiC + 马氏体相变　； 参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：Ti-V-Al合金是一种在航天方面极具潜力的形状记忆合金。目前Ti-V-Al形状记忆合金弹性模量低,用于武器装备中复合材料结构连接时在低负载情况下易出现连接失效问题,限制了Ti-V-Al轻质记忆合金连接紧固件在航天器连接结构中的应用。本文借鉴了复合材料的思路,通过原位自生的方式向Ti-13V-3Al合金中引入了增强相以提高合金的弹性模量与屈服强度。论文系统研究了不同增强相类别及体积分数的复相Ti-V-Al记忆合金的组织结构、马氏体相变及其热循环稳定性、力学性能和形状记忆效应。通过热力学计算可以得出Ti-TiB_2体系在合金中引入的增强相为TiB、Ti-B4C体系在合金中引入的增强相为TiB、TiC。固溶态复相Ti-V-Al记忆合金的室温组织为α"马氏体与增强相组成。增强相的引入细化了合金晶粒,TiB在合金中多为纤维状,一部分为颗粒状,TiC在合金中为颗粒状。随着增强相体积分数增加,TiC的数量和尺寸随之增大,颗粒状TiB的数量随之增大,在体积分数为0.5%~5%时,纤维状TiB的长径比先增大后减小,在体积分数为1%时达到最大。随着增强相的引入,复相Ti-V-Al记忆合金马氏体逆相变温度升高、热稳定性提高。增强相体积分数增加,固溶态复相Ti-V-Al记忆合金马氏体逆相变温度Ap升高。以Ti-B4C体系添加增强相对于合金热稳定性的提高要强于Ti-TiB_2体系。当增强相体积分数增加为0.5%时,合金的马氏体热稳定性最好。增强相体积分数为0.5%时,TiB与TiC共同作为增强相的强化效果要好于TiB单一增强相的强化效果。随着增强相体积分数的增加,合金的延伸率逐渐下降,弹性模量与屈服强度逐渐上升,抗拉强度先增大后减小。合金在增强相体积分数为0.5%时综合力学性能最佳。随着增强体体积分数的增加,合金的记忆效应先增大后减少,在增强体体积分数为1%时达到最大。
[Abstract]:Ti-V-Al alloy is a shape memory alloy with great potential in spaceflight. Due to the low elastic modulus of Ti-V-Al shape memory alloy (SMA), the connection failure of Ti-V-Al shape memory alloy (SMA) is easy to occur in the case of low load, which limits the application of Ti-V-Al light memory alloy fastener in spacecrafts. In order to improve the elastic modulus and yield strength of Ti-13V-3Al alloy, the reinforcement phase was introduced into Ti-13V-3Al alloy in situ by using the idea of composite material. The microstructure, martensitic transformation and thermal cycling stability, mechanical properties and shape memory effect of multiphase Ti-V-Al memory alloy with different reinforcement phases and volume fraction were systematically studied in this paper. The thermodynamics calculation shows that the reinforcement phase introduced in Ti-TiB _ 2 system is TiB- Ti-B4C system, and the reinforcement phase is TiB-B4C system. The room temperature microstructure of solid solution multiphase Ti-V-Al memory alloy is composed of 伪 "martensite and reinforcement phase." With the introduction of the reinforcing phase, the grain size of TIB in the alloy is mostly fibrous, and some of the TIB is granular in the alloy. With the increase of the volume fraction of reinforcing phase, the number and size of tic increase, and the number of granular TIB increases. When the volume fraction is 0.5 ~ 5, the aspect ratio of fibrous TIB increases first and then decreases, and reaches the maximum when the volume fraction is 1. With the introduction of the reinforcing phase, the reverse transformation temperature of martensite and the thermal stability of the multiphase Ti-V-Al memory alloy are increased. The increase of volume fraction of reinforcing phase increases the temperature of inverse transformation of martensite in solid solution Ti-V-Al memory alloy. The increase of thermal stability of Ti-B4C system is stronger than that of Ti-TiB-2 system. When the volume fraction of reinforcing phase is increased to 0.5, the thermal stability of martensite is the best. When the volume fraction of reinforcing phase is 0.5, the strengthening effect of TIB and tic as reinforcing phase is better than that of TIB single reinforcing phase. With the increase of the volume fraction of the reinforced phase, the elongation of the alloy decreases gradually, the elastic modulus and yield strength increase gradually, and the tensile strength increases first and then decreases. The alloy has the best comprehensive mechanical properties when the volume fraction of reinforcing phase is 0.5. With the increase of the volume fraction of the reinforcements, the memory effect of the alloy first increases and then decreases, and reaches the maximum when the volume fraction of the reinforcements is 1.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG139.6
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本文编号：2080468