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

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Title:	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
Authors:	劉國政;Guo-Jheng Liou
Contributors:	機械工程研究所
Keywords:	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
Date:	2008-06-30
Issue Date:	2009-09-21 12:01:41 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	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.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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