退火溫度對形狀記憶合金機械性質及其球面壓痕之影響研究

Effect of Annealing Temperature on the Mechanical Properties and the Spherical Indentation of NiTi Shape Memory Alloy

談宗翰(Tsung-Han Tan)

指導教授 ： 李春穎

國立臺北科技大學/機電學院/製造科技研究所/碩士(2012年)

摘要

鎳鈦合金又稱形狀記憶合金(簡稱SMA)，此材料具有形狀記憶效應，記憶效應可藉由溫度的升降所引起的相變化來驅動。此種具有形狀記憶效應之表面，可以利用類似勃氏硬度計之球面壓痕方式，在SMA材料表面產生殘留應力場，而利用材料之麻田散體-沃斯田體相變化產生互相影響，使SMA材料之表面具有形貌不同的效果。本研究主要探討如何實行SMA材料之拉伸試驗，取出不同溫度下的材料參數，並研究退火溫度對SMA材料的相變化之影響；接著探討形狀記憶合金之球形壓痕深度的可逆變化，在低溫相(麻田散體)有較深的凹痕深度，而在高溫相(沃斯田體)則有較淺的凹痕深度。本研究發現欲想造成SMA表面形貌的改變，可於SMA材料表面製造殘留應力場，利用高低溫之間的相轉換，達到理想起伏效果。本實驗利用電源供應器加熱至接近A_f溫度點，凹痕皆能回復至趨近於平坦處。

關鍵字

形狀記憶合金 ； 超彈性 ； 可調變表面形貌

並列摘要

NiTi alloy is also called shape memory alloy (SMA). Its shape memory effect is derived from the phase transformation by the control of temperature. With the similar spherical indentation produced in the measurement of Brinell hardness, a surface topology inherited with residual stress was obtained on the polished SMA. Following the usual controlled heating performed in the SMA, the indented surface could nearly return to its flat surface configuration as the SMA went through the martensite to austenite transformation. This study firstly focused on how to implement the SMA material tensile test at different controlled temperatures. Thus, the associated mechanical properties at different temperatures were obtained, and the effect of annealing temperature on the SMA phase transformation was investigated. The thus formed spherical indents in shape memory alloys can have reversible depth change, deeper depth in the martensitic phase at low temperature and shallower depth in the austenitic phase at high temperature. Thus, by controlling the temperature of the SMA, a surface with tunable morphology was demonstrated feasible.

並列關鍵字

Shape Memory Alloy ； Superelasticity ； Tunable Surface Morphology

參考文獻

[15] 劉人毅，形狀記憶合金之球面壓痕行為研究，碩士論文，國立台北科技大學機電整合研究所，台北，2011。

[1] Z.G. Wang, X.T. Zu, P. Fu, J.Y. Dai, S. Zhu, L.M. Wang, "Two-way shape memory effect of TiNi alloy coil extension springs," Materials and Engineering A360, 2003, pp.126-131.

[4] Sia Nemat-Nasser, Wei-Guo Guo, "Superelastic and cyclic response of NiTi SMA at various strain rates and temperatures," Mechanics of Materials 38, 2006, pp.463-474.

[6] Li-Yu Tseng, An-Shik Yang, Chun-Ying Lee and Chang-Yu Hsieh, "CFD-based Optimization of a Diamond-Obstacles Inserted Micromixer with Boundary Protrusions," Engineering Applications of Computational Fluid Mechanics Vol.5, No.2, 2011, pp210-222.

[8] J.A. Shaw, C.B. Churchill and M. AIadicola, "Tips and Tricks for Characterizing Shape Memory Alloy Wire: Part 1-Differential Scanning Calorimetry and Basic Phenomena," Experimental Techniques, September/October 2008.