含纳米相Ti-Ni-Cu形状记忆合金薄膜的阻尼减振微观机理研究

The damping and passive vibration control in the micrometer or nanometer scale are the keys to get safer and more reliable ultrasensitive micro-mechine and Micro-Electro-Mechanical System(MEMS). Ti-Ni-Cu shape memory alloy thin films are considered to be the one of the most promosing materials in this field because the stress-induced martensitic transformaiton takes place during the external stress. In this proposal, we try to adjust the damping properties by nanoscale precipitates in Ti-Ni-Cu alloy thin films in order to achieve high strength and high damping properties. Ti-Ni-Cu thin films will be prepared by magnetron sputtering. The nanoscale precipitates with the different types, shapes, size and distribution can be obtained by changing the chemical compositions and the crystallization treatment parameters. The effects of nanoscale precipitates on stress-induced martensitic transformation, microstructure, interface structure and interface movement, superelasticity behaviors and damping properties will be systematically studied. The principles and mechanisms of the influences of nanoscale precipitates on damping properties will be clarfied. The relationship among the characteristics of nanoscale precipitates, stress-induced martenstic transformation and damping will be set up. The micro-mechanism of damping vibraion attenuation of Ti-Ni-Cu alloy thin films containing nanoscale precipitates will be clarified. These studies will be benefical to the damping vibration attenuation in micro-machines and MEMS.

微纳米尺度下超灵敏的微机械和微机电系统（MEMS）中的阻尼减振是保证其精度和安全可靠性的关键。Ti-Ni-Cu形状记忆合金薄膜在外力或交变载荷作用下发生应力诱发马氏体相变，吸收能量，应用前景广阔。本项目拟采用磁控溅射方法制备Ti-Ni-Cu合金薄膜，通过调节化学成分和晶化工艺，获得不同类型、形状、尺寸和分布的纳米析出相，在Ti-Ni-Cu形状记忆合金薄膜中同时获得高强度和高阻尼性能。系统研究纳米析出相对应力诱发马氏体相变、组织结构、界面结构及界面运动、超弹性行为和阻尼特性的影响规律；阐明交变载荷作用下纳米相对薄膜应变滞后于应力周期性变化以及弹性势能衰减的影响规律，揭示纳米析出相对Ti-Ni-Cu合金薄膜阻尼减振影响的微观机理，为微纳米尺度下的阻尼减振奠定理论基础。

如何使Ti-Ni-Cu合金薄膜兼具高阻尼和高强度是拓展其在微纳尺度阻尼减振领域应用的瓶颈与关键。采用磁控溅射法制备非晶态的Ti-Ni-Cu合金薄膜，随后晶化处理，在合金薄膜中获得不同类型、形状、尺寸和分布的纳米尺度的析出相，调节退火温度，获得高阻尼特性和大完全可恢复应变，获得的主要进展包括：1. 系统研究了含有不同纳米相的Ti-Ni-Cu合金薄膜的组织结构和马氏体相变行为，阐明了纳米尺寸析出相对微观组织的影响规律。2. Ti-Ni-Cu合金薄膜经适当的晶化处理后，薄膜内部析出相的变化规律为：GP区→圆盘状Ti2Cu相+球状Ti2Ni相→球状Ti2Ni相，纳米析出相改变基体中的(Ni+Cu)/Ti比，因而导致合金薄膜的相变温度的变化。3. 揭示了纳米相对Ti-Ni-Cu合金薄膜应力诱发马氏体相变、超弹性及阻尼特性的影响。含有析出相的Ti-Ni-Cu合金薄膜在恒应力拉伸中呈现优异的力学性能，应变达到7 %时，仍未出现不可恢复应变。另外，在母相状态下拉伸时，其超弹性应变可达到8 %以上，远高于不存在纳米析出相的薄膜。其在-50 ℃~150 ℃的阻尼测试中，随着退火温度的升高，最大内耗值也随之增加，最高tanδ可以达到0.18。本项目为开发微纳米下高性能的形状记忆合金薄膜（薄带）阻尼减振材料提供了新的思路和理论基础。本项目发表SCI论文6篇（其中JCR一区2篇，综述论文1篇）；培养博士生1人，已毕业1人；硕士生8人，已毕业2人。