English  |  正體中文  |  简体中文  |  Items with full text/Total items : 26988/38789
Visitors : 2343383      Online Users : 41
RC Version 4.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
Scope Adv. Search
LoginUploadHelpAboutAdminister

Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/42711

Title: FeCoNi-基五元高熵合金的氧化行為之研究
The oxidation behavior of FeCoNi-based quinary high-entropy alloys
Authors: Chu, Kuang-Po
朱光柏
Contributors: NTOU:Institute of Materials Engineering
國立臺灣海洋大學:材料工程研究所
Keywords: FeCoNi基高熵合金;γ-Al2O3;θ-Al2O3;α-Al2O3;拋物線律
FeCoNi-based quinary high-entropy alloys;γ-Al2O3;θ-Al2O3;α-Al2O3;Parabolic-rate-law
Date: 2015
Issue Date: 2017-05-24T08:17:31Z
Abstract:   本研究分兩部分探討FeCoNi基合金經表面滲鋁或添加不同鋁之元素的高溫氧化行為。其一是探討FeCoNi等莫耳合金經三種不同活化劑之表面改質後在950oC空氣下的氧化行為,其研究結果顯示,三種活化劑改質的合金之氧化動力學皆呈現二段式拋物線律,其中,最佳的表面鋁化參數為選用63%Al2O3-30%(Fe-Al)合金-7%AlF3(以上皆粉末),並於850oC通入200 cc/min氬氣且持溫4小時;整體而言,改質後合金的氧化速率較FeCoNi原材可減緩約3-5個數量級(依活化劑成份不同而異),說明表面鋁化改質有效提升FeCoNi之高溫抗氧化性能。由XRD及SEM對氧化物截面分析得知,經滲鋁後合金的氧化層主要是α-Al2O3,而它的生成是改質合金的氧化速率降低之主因。   本研究第二部分亦探討三種FeCoNiCrAlx(其中,x= 0.3, 1.0, 及 1.5)五元高熵合金在800~ 1000oC之空氣氧化行為,其研究結果顯示,三種合金在所有溫度下的氧化動力學皆遵守拋物線率;且合金的氧化速率常數(kp值)隨溫度上升而加快,但隨鋁含量增加而減緩。經比較發現,在1000oC下,五元合金皆比四元FeCoNiCr等莫耳合金有較低的氧化速率值(約減緩4至5倍),說明添加Al能有效提升合金之抗高溫氧化性能。三種合金在800~ 1000oC氧化後的表面生成物以α-與θ-Al2O3為主,另有少量的γ-Al2O3及FeAl2O4;而由短時間氧化測試得知,五元高熵合金氧化初期生成θ-Al2O3,但隨時間增加,α-Al2O3的含量也相對地增加。
  The aim of this study is to investigate high-temperature oxidation behavior of the aluminized FeCoNe-based alloy with various activators and the FeCoNiCrAlx alloys (where x=0.3, 1.0, and 1.5). The results indicated that the oxidation kinetics of all the aluminized alloys at 950oC in dry air followed the two-stage parabolic-rate law, and the optimal parameters for the aluminized process was to heat the FeCoNi alloys at 850oC for 4 hr in 63% Al2O3-30% (Fe-Al)-7% AlF3 mixture powders with an Ar-gas flow rate of 200 cc/min. The oxidation rates of the aluminized alloys were significantly lower than the untreated FeCoNi substrate by 2.9 to 5.1 orders of magnitude strongly depending on the activator. Based on XRD and SEM analyses, α-Al2O3 was the major scale formed on the aluminized alloys, whose formation was responsible for the significant reduction of the oxidation rate with respect to the un-treated FeCoNi alloy.   In addition, the oxidation behavior of the three FeCoNiCrAlx high-entropy alloys (HEAs) was studied over the temperature range of 800~ 1000oC in dry air. The results showed that the oxidation kinetics of all the HEAs followed the parabolic-rate law, with their oxidation rate constants (kp values) increased with increasing temperature, but decreased with increasing Al content. It was found that the kp values of the quinary HEAs were significantly lower than those of the FeCoNiCr equi-molar alloy by a factor of 4 to 5 at 1000oC. The scales formed on the quinary HEAs consisted of a heterophasic mixture of mostly α- and θ-Al2O3 and minor γ-Al2O3 and FeAl2O4 at 800~ 1000oC. The θ-Al2O3 phase always started to grow on the alloy surface at the beginning of oxidation, while the amount of α-Al2O3 phase detected steadily increased with increasing exposure of time.
URI: http://ethesys.lib.ntou.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=G0010255003.id
http://ntour.ntou.edu.tw:8080/ir/handle/987654321/42711
Appears in Collections:[材料工程研究所] 博碩士論文

Files in This Item:

File Description SizeFormat
index.html0KbHTML49View/Open


All items in NTOUR are protected by copyright, with all rights reserved.

 


著作權政策宣告: 本網站之內容為國立臺灣海洋大學所收錄之機構典藏,無償提供學術研究與公眾教育等公益性使用,請合理使用本網站之內容,以尊重著作權人之權益。
網站維護: 海大圖資處 圖書系統組
DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - Feedback