【正文】 畢業(yè)論文 院系名稱 材料科學(xué)與工程 2021 年 6 月 7 日 論文題目 熔體狀態(tài)對 BiTeSe 系熱電材料組織與性能的影響 學(xué)生姓名 張宗委 學(xué) 號 2021211052 專業(yè)班級 材料成型 3 班 指導(dǎo)教師 祖方遒，朱彬 目錄 中文摘要 ........................................................................................................................ 1 英文摘要 ........................................................................................................................ 2 1 緒論 .......................................................................................................................... 3 引言 ..................................................................................................................... 3 熱電材料 ............................................................................................................. 3 熱電效應(yīng) ...................................................................................................... 4 熱電優(yōu)值 ...................................................................................................... 5 BiTe 基熱電材料 ................................................................................................. 6 Bi2Te3基熱電材料的結(jié)構(gòu)特征 .................................................................... 6 n 型 Bi2(Te,Se)3材料的制備 ........................................................................ 6 熔體結(jié)構(gòu)及熱處理 ............................................................................................. 7 液態(tài)金屬的結(jié)構(gòu)與研究方法 ...................................................................... 7 熔體熱處理 .................................................................................................. 8 主要研究內(nèi)容 ..................................................................................................... 8 2 試驗方法 .................................................................................................................. 9 電阻率的測量 ..................................................................................................... 9 凝固試驗 ........................................................................................................... 11 實驗裝置 .................................................................................................... 11 實驗原理 .................................................................................................... 11 熱處理規(guī)程 ................................................................................................ 11 實驗步驟 .................................................................................................... 12 注意事項 .................................................................................................... 12 Seebeck 系數(shù)的測量 .......................................................................................... 12 測量裝置及原理 ........................................................................................ 12 實驗原理 .................................................................................................... 13 實驗步驟 .................................................................................................... 14 注意事項 .................................................................................................... 14 試樣組織結(jié)構(gòu)觀察 ........................................................................................... 14 X 射線衍射試驗 ......................................................................................... 14 掃描電鏡拍攝 ............................................................................................ 14 3 實驗結(jié)果與分析 .................................................................................................... 15 BiTeSe 系熱電材料的電阻率 溫度行為 .......................................................... 15 實驗結(jié)果 .................................................................................................... 15 結(jié)果分析 .................................................................................................... 16 BiTeSe 系熱電材料的合金液固相關(guān)性 ........................................................... 17 ..................................................................... 17 ..................................................................... 20 熔體處理對 BiTeSe 系熱電材料熱電性能的影響 ......................................... 23 熔體處理對 ....................................... 23 熔體處理對 ....................................... 24 4 全文總結(jié) .................................................................................................................. 26 致謝 .............................................................................................................................. 26 參考文獻 ...................................................................................................................... 28 1 熔體狀態(tài)對 BiTeSe系熱電材料 組織與性能的影響 摘要： 本文以 ，應(yīng)用直流四電極方法，通過分析熔體的電阻率 溫度曲線，探索出溫度誘導(dǎo)的熔體結(jié)構(gòu)轉(zhuǎn)變發(fā)生的可能性及可逆性，并確定出轉(zhuǎn)變的溫度區(qū)間。并在此基礎(chǔ)上，通過改變其熔體熱歷史，采用熱分析法、凝固組織觀察、 XRD、電鏡掃描等實驗手段，探索熔體狀態(tài)對 BiTeSe 系熱電材料微觀組織與性能的影響。主要結(jié)論如下： 根據(jù) ρT 曲線的異常行為，推斷熔體發(fā)生了溫度誘導(dǎo)的不可逆的熔體結(jié)構(gòu)轉(zhuǎn)變，轉(zhuǎn)變溫度區(qū)間大體為 800℃ 900℃ 。 凝固熱分析及組織表征揭示， 態(tài)的改變對其凝固行為和組織有明顯的正面作用：形 核和生長過冷度增大，形核率明顯提高；凝固組織明顯細(xì)化，擇優(yōu)取向減弱，晶粒分布更加均勻無序。 ，試樣的 Seebeck 系數(shù)增大，電阻率降低，功率因子顯著提高，熱電性能得到改善。 關(guān)鍵詞： 熱電材料；熔體狀態(tài)；凝固行為；凝固組織；熱電性能 2 Abstract: In this paper, the DC fourelectrode method was used to explore the temperature dependence of electric resistivity of n type thermoelectric alloys and and the possibility of melt structure transition, reversibility, and temperature ranges were also investigated. On this basis, by means of thermal analysis, solidification microstructure and Xray diffraction, we studied the effect o