熱機處理對Fe-13Mn-5Si-12Cr-5Ni/5Cu 形狀記憶合金之影響

Effects of Thermo-Mechanical Treatment on a Fe-13Mn-5Si-12Cr-5Ni/5Cu Shape Memory Alloy

吳維仁(Wei-Jen Wu)

指導教授 ： 林新智

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.02364

摘要

Fe-13Mn-5Si-12Cr-5Ni形狀記憶合金擁有良好記憶效應，研究中探討熱機處理，析出物行為以及微結構對記憶效應的影響。實驗結果顯示: γ-沃斯田鐵，ε-麻田散鐵以及α-肥粒鐵同時存在於熱輥軋試片，5%冷輥軋及15%冷輥軋試片中。試片經600℃時效2小時後，達到最佳記憶效應。對熱輥軋，5%冷輥軋及15%冷輥軋試片，最佳記憶效應分別為99%, 90% 以及89% 。然而，繼續提高時效溫度產生的現象，如:整齊排列的析出物成長及消失，合金晶粒成長…等，不利於記憶效應，因此回復率下降。
時效過程中，析出物容易析出於缺陷上，尤其是變形引入的缺陷，如:差排帶，曡差帶以及γ/ε界面，均為析出物於時效時易優先成核析出的位置。研究中發現數種析出物析出於Fe-13Mn-5Si-12Cr-5Ni試片。熱輥軋試片經600℃時效2小時後，較大的析出物為M7C3；較小的(奈米)析出物為(Fe-Si)Cx。5%及15%冷輥軋試片經600℃時效2小時後，觀察到的析出物為M2C。
另外，對於Fe-13Mn-5Si-12Cr-5Cu試片，經600℃時效2小時後達到最佳記憶效應96%。此時在合金內部較大的析出物為M6C，較小的(奈米)析出物為FeSi2。

關鍵字

Fe-Mn-Si-Cr-Ni/Cu 形狀記憶合金熱機處理麻 ； 田散鐵變態 ； 析出物 ； 疊差

並列摘要

Effects of thermo-mechanical treatment on the microstructure, precipitation behavior and shape memory performance of a Fe-13Mn-5Si-12Cr-5Ni shape memory alloy were investigated. Experimental results show that the γ austenite, ε martensite and α phase coexist in the as-hot-rolled, 5% cold-rolled and 15% cold-rolled specimens. Under the condition of 600℃ aging for 2 hours, specimens exhibit the optimal recovery ratio. For as-hot-rolled, 5% and 15%cold-rolled specimens, the optimal recovery ratios can reach 99%, 90% and 89%, respectively. But, when aging temperature is more increased, the recovery ratios decrease due to some detrimantal factors such as growth and disappearance of well-aligned precipitates, grain growth and etc.
The deformation-induced defects, such as dislocation bands, stacking faults and γ/ε interfaces are preferential sites for nucleation of the precipitates during aging. In this study, several kinds of precipitates are found in the Fe-13Mn-5Si-12Cr-5Ni alloy. For as-hot-rolled Fe-13Mn-5Si-12Cr-5Ni alloy with subsequent aging at 600℃ for 2 hours, the bigger precipitate is identified as M7C3, and the nano-precipitate is identified as (Fe-Si)Cx.. For 5% cold-rolled and 15% cold-rolled specimens with subsequent aging at 600℃ for 2 hours, the only one precipitate observed is identified as M¬2C.
In addition, for Fe-13Mn-5Si-12Cr-5Cu, the optimal condition for shape recovery ratio is 600℃ for 2 hours and it can reach 96%. Bigger precipitate in hot-rolled Fe-13Mn-5Si-12Cr-5Cu with subsequent aging at 600 ℃ is identified as M6C, and nano-precipitate in the same specimen is identified as FeSi2.

並列關鍵字

Fe-Mn-Si-Cr-Ni/Cu shape memory alloy ； thermo-mechanical treatment ； martensitic transformation ； precipitate, ； stacking fault

參考文獻

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