Ti49.7Ni50.3形狀記憶合金冷軋延之 顯微結構研究
Date Issued
2004
Date
2004
Author(s)
Lee, Jang Hao
DOI
zh-TW
Abstract
本實驗使用VAR熔配單一成分之Ti49.7Ni50.3形狀記憶合金，鑄錠試片經均質化以及熱滾軋後，在900℃進行固溶處理，之後淬至冰水中，再進行不同縮減量的冷滾軋，利用DSC和XRD量測以及穿透式電子顯微鏡觀察其不同縮減量之顯微組織的變化。
實驗結果得知TiNi形狀記憶合金之變形調適機制，主要是麻田散體兄弟晶以雙晶型式作調適。隨著不同的冷軋延量，其雙晶調適機制也隨之改變。在較低的冷軋延量（5％）時，主要以 <011> typeⅡ twinning做調適。當冷軋延量增加時（15％），麻田散體次組織帶內之調適雙晶型式逐漸改變，不再以 <011> typeⅡ twinning為主，出現一些交插之針狀雙晶平板，以及大量的差排和缺陷。當冷軋延量達30％時，局部區域出現非晶質化，且可能有應力誘發母相SIP(stress-induced parent phase)的機制發生。
A Ti-50.3at.％Ni shape memory alloy was melted by VAR in this study. The ingot was homogenized and hot-rolled at 850℃. After solution-treatment at 900℃ for 1 h followed by quenching into 3℃ water, the specimens were cold-rolled at room temperature to various reduction in thickness. The microstructure and crystal structure of cold-rolled specimens were analyzed by Differential Scanning Calorimeter (DSC), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM).
The results shows that the deformation mechanism of TiNi SMA is dominant by twinning accommodation in the martensite variants . The twinning mode is changed with degree of cold-working . At slight cold reduction (5％) , the <011> typeⅡ twinning mode is dominant .However at heavy cold reduction (15％), the twinning modes inside the martensite substructural bands are different. Some cross-hatched twinning plates , heavy dislocation and defects are observed. When the cold-reduction finally reaches 30％ , mechanical amorphisation happens in local
regions. At the same time , the stress-induced parent phase also happen.
Subjects
應力誘發母相
SIP
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-93-R91527029-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):809af558fb3e78aaa556dfe30555ceba