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標題: | 時效對Ti49.5Ni48.5Fe2及Ti49Ni49Fe2形狀記憶合金相變態行為影響之研究 Transformation Characteristics of Aged Ti49.5Ni48.5Fe2 and Ti49Ni49Fe2 Shape Memory Alloys |
作者: | Bo-Yang Huang 黃博揚 |
指導教授: | 吳錫侃(Shyi-Kaan Wu) |
關鍵字: | TiNiFe形狀記憶合金,時效處理,析出物,變態順序,顯微組織,硬度, TiNiFe shape memory alloy,aging treatment,precipitates,transformation sequence,microstructure,hardness, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 本文研究Ti49Ni49Fe2與Ti49.5Ni48.5Fe2 (原子比)SMAs,經900°C固溶處理1小時淬火後,進行時效處理,針對其變態順序、硬度及顯微組織加以探討。研究結果顯示,固溶處理後淬火之Ti49Ni49Fe2 SMA在DSC曲線上觀察不到相變態,而同樣條件之Ti49.5Ni48.5Fe2 SMA則可觀察到B2↔R↔B19’的二階相變態。固溶處理淬火後在400°C~500°C時效兩者皆會產生B2↔R一階相變態,其與Ti3Ni4之析出有關。在硬度量測的結果中,Ni含量較高者不僅其固溶處理後淬火之硬度較高,其析出硬化的效果也較佳。從顯微組織觀察的結果來看,Ni含量較高者其Ti3Ni4之析出分布較密集,故有較好的析出硬化效果。然而在550°C時效的結果中,即使時效至500小時,Ti49Ni49Fe2 SMA在DSC曲線上仍觀察不到相變態,硬度值也無太大的變化,雖有Ti3Ni4之析出,但其大小太大,不具備整合性界面之應力場;而Ti49.5Ni48.5Fe2 SMA的變態順序則變為B2↔R,但也觀察不到Ti3Ni4所誘發之B2↔R相變態的產生,且硬度也無太大的變化,應與Ti3Ni4之析出量太少有關。從顯微組織的觀察結果可以發現,時效的溫度越高,Ti3Ni4析出物的數量及分布越稀疏,但其成長較為快速。此外,Ni含量較高之Ti49Ni49Fe2 SMA其Ti3Ni4析出物之數量明顯多於Ni含量較低之Ti49.5Ni48.5Fe2 SMA。 Ti49.5Ni48.5Fe2 and Ti49Ni49Fe2 (in at.%) SMAs are solution-treated, quenched and aged at 400°C ~550°C to study the effects of different aging temperatures and times on SMA’s transformation sequence, hardness, microstructure, etc. Experimental results of the DSC test indicate that there is no transformation peak in solution-treated Ti49Ni49Fe2 SMA, but shows B2↔R↔B19’ transformation sequence in solution treated Ti49.5Ni48.5Fe2 SMA. In addition, for specimens of both SMAs aged at 400°C ~ 500°C, Ti3Ni4 precipitates(ppts) occur and induce new B2↔R-phase transformation. According to hardness test results, the specimen with higher Ni content displays the better effects of solution strengthening and precipitation hardening. However, for Ti49Ni49Fe2 SMA aged at 550°C, there is no transformation peak appearing on DSC curve, in which Ti3Ni4 ppts can also be observed, but their size is too large and losts the coherent stress to induce R-phase transformation. For Ti49.5Ni48.5Fe2 SMA aged at 550°C, the amount of Ti3Ni4 ppts is not enough to induce R-phase transformation. SEM oberservations indicate that SMAs with higher Ni content have more Ti3Ni4 ppts in the matrix, and the amount of Ti3Ni4 ppts decreases more with the higher aging temperature. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/58461 |
DOI: | 10.6342/NTU202001473 |
全文授權: | 有償授權 |
顯示於系所單位: | 材料科學與工程學系 |
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