Ti50Ni44Cu5Al1形狀記憶合金箔帶之製備與性能研究

Abstract

本研究使用熔融紡絲製程製備TiNi基形狀記憶合金箔帶，結果顯示轉速及壓差能夠大幅影響噴出箔帶的巨觀樣貌及微觀結構。利用熔融紡絲製程製造出的Ti50Ni44Cu5Al1箔帶被觀察到兩個不同種類的性質，兩者的差異應來自噴鑄時的熔融溫度導致的成分差異。第一類為Ti成分較高者，具有明顯相變態且相變態溫度較高；第二類的Ni及Si含量較高，相變態不明顯且相變態溫度低。第一類箔帶的可以在200MPa應力下產生5.8%可回復應變且殘留應變為0.28%，拉伸至應變3%後快速釋放可產生10.5℃的彈熱溫降，適合作為常溫下固態冷媒應用。第二類箔帶噴鑄狀態能在室溫拉伸達應力650MPa及1%的彈性應變量，形狀記憶效應在450MPa的應力下有5.2%可回復應變與僅為0.21%應變殘留，適合在低溫大應力的環境使用。另外數位影像關係法的結果顯示，對箔帶進行表面研磨能使超彈性以及彈性拉伸的應變分布與各區域應變率均勻化，並使相變態起始時機趨同，顯著改善性能表現。

In this study, the melt-spinning technique was employed to fabricate TiNi-based shape memory alloy ribbons. The results demonstrated that the wheel speed and pressure difference significantly influenced the macroscopic appearance and microstructure of the melt-spun ribbons. Two types of Ti50Ni44Cu5Al1 ribbons were fabricated through the melt-spinning process, which were likely attributed to the compositional differences caused by the melting temperature during the melt-spinning process. The first type of ribbon had a higher Ti content, showing a noticeable phase transformation with a higher transformation temperature. On the other hand, the second type had higher Ni and Si contents, with less pronounced phase transformation behavior and a lower transformation temperature. The superelasticity test showed that the first type of ribbon could generate 5.8% recoverable strain under a stress of 200 MPa, with a residual strain of 0.28%. Rapid releasing from 3% strain generated an elastocaloric temperature drop of 10.5℃. It was considered suitable for application as a solid-state refrigerant at room temperature. The second type of ribbon sustained a tensile stress of 650 MPa and an elastic strain of 1% at room temperature. The second type of ribbon showed shape memory effect with 5.2% recoverable strain and only 0.21% residual strain under a stress of 450 MPa, making it suitable for applications in low-temperature and high-stress environments. Furthermore, the results of digital image correlation indicated that surface polishing of the ribbons resulted in a more uniform distribution of strain and strain rate during superelastic deformation. It also led to a synchronization of the phase transformation initiation, significantly improving the performance characteristics.