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

• Main Authors: Tsung-Han Tan, 談宗翰
• Other Authors: 李春穎
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/9qm86s

碩士 === 國立臺北科技大學 === 製造科技研究所 === 101 === 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.