TiNi基合金的阻尼机理及其成分优化

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	TiNi基合金的阻尼机理及其成分优化
	曾建敏
学位类型	硕士
导师	戎利建
	2012
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料加工工程
关键词	Tini基形状记忆合金力学性能阻尼性能抗腐蚀性能 Tini-based Shape Memory Alloy Mechanical Property Daming Capacity Corrosion Resistance
摘要	"在现代工业日趋高速化、精密化发展的同时，人们对生活环境的质量要求越来越高，如何减少振动、降低噪音以提高设备安全性、可靠性并改善居家环境，成为人们日益关注的问题。高阻尼材料，特别是阻尼合金，在减振降噪领域便引起了高度重视，其中TiNi基阻尼合金因兼具形状记忆效应、超弹性、耐高温及抗腐蚀等特点，获得了最广泛的学术研究和工业应用。本论文采用动态力学分析仪（DMA）研究频率f、应变振幅ε及变温速率dT/dt等实验参数对Ti50.1Ni49.9二元合金阻尼性能的影响，研究合金在马氏体态、奥氏体态以及相变温度区间内阻尼性能的变化规律，揭示合金的阻尼来源及其本质。通过添加不同含量的Mo元素、调整Nb含量、改变Ti/Ni原子比等方法，优化TiNiNbMo四元合金的化学成分，从而获得高强高阻尼的TiNiNbMo四元合金。 Ti50.1Ni49.9合金的阻尼性能测试结果表明：当固定频率f=1Hz，应变振幅ε=0.01%时，合金马氏体逆相变阻尼峰的峰值阻尼Q-1相应峰值温度Tp均随dT/dt线性增大；当固定应变振幅ε=0.01%，升温速率dT/dt=3oC/min时，阻尼峰随频率的增大而减小，峰值阻尼Q-1与频率的倒数1/f呈线性关系。这些都与马氏体相变时储存的弹性应变能的释放有关。在频率f=1Hz，升温速率dT/dt=3oC/min的条件下，随应变振幅的增大，Ti50.1Ni49.9合金马氏体态及母相状态下的阻尼逐渐增大，然而马氏体逆相变阻尼峰逐渐减小。通过对相变区间内的阻尼恒温衰减规律的研究，揭示该现象是由瞬态阻尼IFTr随应变振幅的增大而降低造成的。由于外部应力趋于使界面稳定化并抑制逆转变过程中新相界面的产生，故应变振幅越大，一个振动循环过程中产生的新相界面数量越少，IFTr也就随之减小。当IFTr的减小幅度超过相变阻尼和本征阻尼之和（IFPT+IFInt）的增加趋势，阻尼峰IF便随应变振幅的增大而减小。在高强高阻尼合金研制方面，通过成分优化设计，提高TiNi合金在马氏体态下的屈服强度和阻尼性能，提升了TiNi基阻尼合金的实用价值。在固定Ti/Ni=1，Nb含量为8at.%的条件下，添加不同含量的Mo元素进行合金化，形成新型的TiNiNbMo四元合金。结果表明Mo能减小β-Nb与TiNi基体形成的共晶组织，使Nb倾向于以颗粒状在TiNi基体中析出，不但起沉淀强化作用，也增大了合金中的相界面分数，为高阻尼提供发生源。同时通过降低Nb含量至6at.%，并加入1.5at.%的Mo，改变Ti/Ni原子比，研究不同的Ti/Ni比对合金的组织和性能的影响，组织观察结果表明Ti/Ni比的增大使共晶组织进一步减少。DSC相变特性曲线表明合金呈多阶段相变特征，而且在降温及升温过程中，多阶相变贡献阻尼使合金表现高阻尼的温度区间变宽。与TiNi二元合金相比，Ti/Ni=1.08的TiNiNbMo四元合金由于Nb以颗粒状析出而使得其在马氏体态下具有更高的阻尼特性，同时该合金在室温下屈服强度最高，且抗腐蚀性能最优。"
其他摘要	" With the development of modern industry, the safety and reliability of equipments and the improvement of the living environment by suppressing vibration and noise have been highly concerned by human beings. High damping materials, especially the damping alloys, have attracted great attention to suppress vibration and noise. TiNi-based damping alloys have been studied and applied widely since they exhibit unique properties, such as shape memory effect, superelasticity, thermo stability, corrosion resistance and high damping capacity. In this dissertation, the relationship between frequency (f), strain amplitude (ε), heating rate (dT/dt) and the damping capacities of Ti50.1Ni49.9 binary alloy has been investigated by dynamic mechanical analyzer (DMA). Chemical compositions of TiNiNbMo quaternary alloys have been optimized by adjusting Mo, Nb and Ti/Ni atomic ratio. The main results of damping behaviors of Ti50.1Ni49.9 alloy are revealed as the following: The damping peak value and corresponding peak temperature increase approximately linearly with the increasing dT/dt. When f is increased, is a function of the inverse of frequency (1/f) which exhibits linearly increase tendency. When strain amplitude ε is increased, the damping capacities both in martensite and parent phase of Ti50.1Ni49.9 alloy increase while the damping peak value during reverse martensitic transformation decreases. This phenomenon is attributed to the transitory term of damping peak (IFTr) which is ε dependent: the larger the ε is, the less amount of interphases would form during per cycle of vibration, since external stress tends to stabilize martensite and impede the generation of new interfaces. When the decrease of IFTr exceeds the increase of (IFPT+IFInt), the damping peak reduces. For the TiNiNbMo quaternary alloys, the alloying result by adding varying quantities of Mo indicates that, Mo can depress the aggregation of Nb on grain boundaries and lower the eutectic extent which is composed of β-Nb and TiNi matrix. The precipitation of Nb-rich particles in the matrix not only improve the mechanical property but also enlarge the phase interfaces of β-Nb with the matrix, which mainly lead to the high damping. Further alloying is carried out by lowering the Nb content to 6at.%, with 1.5at.% Mo adding and adjusting Ti/Ni atomic ratio. The microstructure observation shows that eutectic is weakened by the increase of Ti/Ni. The DSC test results exhibit multi-stage transformation, which can induce a broader temperature range corresponding the damping peak during cooling or heating process. TiNiNbMo quaternary alloy with Ti/Ni=1.08 shows higher yield strength and better corrosion resistance than those with Ti/Ni=1.03 or 1.13. Meanwhile, the alloy in martensite phase exhibits much higher damping compared with Ti50.1Ni49.9 alloy, which is mainly attributed to the precipitation of Nb-rich particles."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64540
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	曾建敏. TiNi基合金的阻尼机理及其成分优化[D]. 北京. 中国科学院金属研究所,2012.