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    請使用永久網址來引用或連結此文件: http://ir.lib.ncu.edu.tw/handle/987654321/2951


    題名: 添加鈹、鈧之LAZ1110鎂鋰合金經等通道彎角擠製後之微結構及機械性質研究;A study on the Microstructures and Mechanical properties of LAZ1110 Mg-Li alloy containing Sc and Be after Equal Channel Angular Extrusion
    作者: 劉國政;Guo-Jheng Liou
    貢獻者: 機械工程研究所
    關鍵詞: 鎂鋰鋁鋅合金;等通道彎角擠製;微結構;機械性質;Mg-Li-Al-Zn alloys;Equal channel angular extrusion;Microstructure;Mechanical properties
    日期: 2008-06-30
    上傳時間: 2009-09-21 12:01:41 (UTC+8)
    出版者: 國立中央大學圖書館
    摘要: 本論文以LAZ1110鎂合金為基本,添加微量Be、Sc元素,形成LAZ1110、LAZ1110+Sc、LAZ1110+Be及LAZ1110+Be,Sc四種合金,除了觀察添加微量Be、Sc元素對LAZ1110在微結構及機械性質的影響外,亦藉由等通道彎角擠製(ECAE)嘗試細化晶粒及探討擠製後之常溫機械性質、微結構的變化,並對ECAE後材料進行退火處理,觀察微結構及硬度值的變化。 比較四種原材之微結構,LAZ1110合金添加Sc,有晶粒細化的效果。LAZ1110合金添加Be,會產生兩種微結構的影響,晶粒粗大及費德曼組織。在機械性質部分,抗拉強度以LAZ1110+Be最高,達151 MPa,較LAZ1110+Sc的147 MPa高,在此以添加Be產生費德曼組織的析出強化效果較添加Sc的細晶強化好。 四種原材於室溫經ECAE後,LAZ1110合金經120°-RT-C4擠製後,晶粒從25μm細化至11μm,為原材的44%;LAZ1110+Sc合金經120°-RT-C4擠製後,晶粒從18μm細化至9.7μm,為原材的54%;LAZ1110+Be合金經120°-RT-C4擠製後,部分區域出現動態再結晶晶粒組織,大小約為5~20μm,LAZ1110+Be&Sc合金經120°-RT-C4擠製後,晶粒大小變化不大。在機械性質部分,最大抗拉強度出現在LAZ1110+Be經120°-RT-C4擠製後,達175.5 MPa,為原材的1.16倍,伸長率仍有69.7%。 四種材料經120°-RT-C4擠製後之試片,施以50、100、150、200及250℃×30min退火處理後,於LAZ1110+Be,250℃×30min退火條件下觀察到大面積的靜態再結晶,晶粒大小約為4.5μm,且費德曼組織消失。而四種材料退火硬度值於50℃呈現下降的趨勢,而後隨著溫度提升而有漸增的趨勢,50-200℃硬度值均呈平緩漸增,至250℃硬度值產生驟增的現象。 An unprecedented try of adding Sc and Be elements into Mg-Li alloys in order to enhance their strengths has been carried out and the results will be presented. Four Mg-Li alloys; a bare one (11%Li-1%Al-0.5%Zn), the second with Sc, the third with Be and the fourth with both Sc and Be were prepared by vacuum melting processes. They were then homogenized at 350℃, followed by an extrusion for plates. Microstructures and mechanical properties are studied on this as-extruded sample and those subsequently process by equal channel angular extrusion (ECAE) at room temperature. The effect of adding Sc element to the LAZ1110 alloy was refining β grains. The addition of Be element produces two micro-structural effects, grain coarsening and Widmanstatten structure. On the mechanical properties, the maximum tensile strength obtained in LAZ1110+Be is 151MPa.This figure is better than the other of three alloys. LAZ1110 alloy processed under condition, 120°-RT-C4, the size of β grains range from 25μm to 11μm. LAZ1110+Sc alloy processed under condition, 120°-RT-C4, the size of β grains range from 18μm to 9.7μm. LAZ1110+Be alloy processed under condition, 120°-RT-C4, some area of β phase can be find dynamic recrystallization grains. LAZ1110+Be&Sc alloy processed under condition, 120°-RT-C4, the change of β grains were small. On the mechanical properties, LAZ1110+Be alloy processed under condition, 120°-RT-C4,shows the greatest increase in tensile strength about 24.8 MPa.
    顯示於類別:[機械工程研究所] 博碩士論文

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