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標題: | 鉭添加對於Fe-30Mn-6Si-5Cr形狀記憶合金之效應 Effects of Tantalum Addition on Fe-30Mn-6Si-5Cr Shape Memory Alloys |
作者: | Jian-Hong Chen 陳建宏 |
指導教授: | 林新智 |
關鍵字: | Fe-Mn-Si-Cr形狀記憶合金,形狀記憶效應,麻田散鐵變態,鉭元素,固溶強化,析出,疊差, Fe-Mn-Si-Cr shape memory alloys,shape memory effect,martensitic transformation,tantalum,solid solution strengthening,precipitation,stacking fault, |
出版年 : | 2013 |
學位: | 碩士 |
摘要: | Fe-Mn-Si-Cr形狀記憶合金具有良好的加工成形性、良好的形狀記憶效應、以及相對低廉的單位成本。除此之外,Fe-Mn-Si-Cr合金只具有單向記憶效應,一旦經過加熱回復形狀一次後,形狀就不會再隨溫度變化而改變。因此Fe-Mn-Si-Cr合金對於大尺度、只需要一次性變形的機構應用來說,是相當理想的材料。工業上應用的實例如連接管路用的套筒元件、連接軌道的魚尾板、以及鉚釘。本研究藉由添加0.1wt%以及1.0wt%的鉭元素於Fe-30Mn-6Si-5Cr合金中,搭配2小時500到800℃的時效處理,來改善其形狀記憶效應。其中添加1.0wt%鉭並經過2小時700℃時效處理後的合金,與未經添加與熱處理的合金相比,有最高的形狀回復率,其增加量達16%。經過時校處理後,在γ基地發現有TaC與χ相兩種不同的第二相顆粒,在不同的鉭添加與時效處理溫度下,這些析出物的大小與分佈也隨之不同。本研究發現,鉭添加對於改善形狀記憶效應的機制有以下數種:固溶強化與析出第二相強化 γ奧氏體母相、γ奧氏體母相的晶粒細化、析出物在γ晶粒內對於不同方向ε麻田散鐵成長的區隔效應、以及增加γ母相內的疊差機率。 Fe-Mn-Si-Cr based shape memory alloys (SMAs) have desirable formability, moderate shape memory effect (SME) and low cost. This makes ferrous SMAs highly potential in large-scaled applications such as pipe coupling, rail fish plates, and other smart construction methods. Also, Fe-Mn-Si-Cr alloys only have one-way shape memory effect, which is ideal for applications that require only-one-time shape recovery as the fixed structure shape. In this study, the shape memory effect of Fe-30Mn-6Si-5Cr (in wt%) SMAs are improved by adding 0.1 wt% and 1.0 wt% Ta along with ageing treatment from 500 to 800℃ for 2 hours. 1.0 weight percent Ta addition followed by ageing at 700℃ for 2 hours increases recovery ratio up to 16 percent. Precipitate particles such as TaC and χ were found in the aged samples with different size and distribution in the γ matrix. Mechanisms of improving SME by Ta addition are proposed in the work: Solid solution and precipitation strengthening on the γ matrix, grain refining of γ parent phase, domain effect of precipitate particles, and increasing of stacking fault probability. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/61552 |
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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