间隙原子调节Ti-Ni-Cu基形状记忆合金薄膜弹热效应的研究

形状记忆合金展现出优良的弹热效应，以其发展的制冷模式是当前最有希望发展的固体相变制冷模式之一，具有绿色环保、节能高效和稳定可靠等诸多优点。形状记忆合金薄膜与体材料相比具有大的表面/体积比，可极大缩短热传导的时间，提高热循环的频率，因此在微型制冷领域应用潜力巨大。本项目提出采用间隙原子调控Ti-Ni-Cu基形状记忆合金薄膜弹热效应的研究思路。拟向Ti-Ni-Cu基记忆合金中引入C、N、O和B等间隙原子，系统研究间隙原子的类型与浓度等对弹热过程中绝热温度变化和熵变的影响规律，查明间隙原子对相变潜热、比热容等热力学参数的影响规律与机制，探索提高弹热效应的有效方法与途径；研究间隙原子对微观结构和应力诱发马氏体相变行为的影响因素与规律，揭示微结构-相变-弹热效应之间的内在关联性。为研发绿色、节能、高效的新型形状记忆合金弹热材料提供新思路和新方法，促进其在电子芯片和生物医疗等微制冷系统中的应用。

Shape memory alloys (SMAs) show excellent elastocaloric effect and are considered as one of promising materials for solid state refrigeration. SMAs are environment-friendly, energy-saving, efficient and safe. Compared with SMA bulk materials, SMA thin films have large surface-to-volume ratio, which is advantageous in expediting heat transfer and consequently allows for higher cycling frequencies. Therefore, SMA thin films are attractive for solid state cooling applications in micro-systems. In the present proposal, we try to tailor the elastocaloric effect of Ti-Ni-Cu based SMA thin films by doping of C, N, O and B atoms. The method to improve the elastocaloric effect of Ti-Ni-Cu based SMA thin films will be explored. We will systematically study the effects of interstitial atoms on the temperature change, entropy change, phase transformation latent, specific heat capability. The reasons for the effects of interstitial atoms on the microstructure, interface between parent phase and martensite, interface mobility, stress-induced martensitic transformation behaviors and superelasticity will be clarified. The relationship among the microstructure, phase transformation and elastocaloric effect will be investigated. The present proposal will provide new idea and new method for developing new type SMA thin films with high performance for the micro solid state cooling applications in electronic chips, lab-on-chip, minimally invasive surgery and etc.