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Student Number 963303016
Author Chia-hung Kao(高嘉宏)
Author's Email Address No Public.
Statistics This thesis had been viewed 728 times. Download 625 times.
Department Executive Master of Mechanical Engineering
Year 2010
Semester 2
Degree Master
Type of Document Master's Thesis
Language zh-TW.Big5 Chinese
Title Microstructures and Mechanical Properties of LAZ1110 Mg-Li Alloy after A Feed Rate of Heavy Rolling Reduction
Date of Defense 2011-04-12
Page Count 74
Keyword
  • Grain refining
  • Magnesium-Lithium alloy
  • Rolling
  • Solution treatment
  • Abstract This study purpose uses a different feed rate of rolling reduction, to research and discuss the microstructures and mechanical properties of a series of super light magnesium-lithium alloys. Adding Li raises Mg alloy formability and promotes improving cool and heat deformation ability. Previous researches indicate that Mg-Li alloys lack of strength and work hardening, therefore we wish to increase its strength and work hardening by adding Sc and Be into the alloy, creating two alloys, LAZ1110, LAZ1110+ Be &Sc, respectively.
      And we also use different processes to enhance the mechanical properties, such as solid solution treatment and cold work strengthening. Each material is rolled reduction by 30%, 60% and 90%. Experimental rolling reduction feed rate uses 10% and 15% to compare the test data difference. After Mg-Li alloy is extrusion plus solid solution and then cold rolling. Due to the superimposition effect of solid solution strengthening and cold work strengthening, the material after 90% rolling reduction of a feed rate 15% can obtain a maximum strength of about 281MPa. It’s apparently higher than a maximum about 246MPa of 90% rolling reduction of a feed rate 10%. Follow prior thesis, we can infer if the material is extruded, solid solution treated and cold rolled before aged. The material aged under room temperature after 20~40hrs will have peakaging with maximum tensile strength.
      In microstructures, experimental results show that two alloys change from α+β-phase to a single β-phase after solid solution treatment. After rolling the grains are elongated and α-phase will precipitate with increasing rolling percentage. The two alloys’ specimens after extrusion, solid solution and cold rolling were annealed at 50、100、150、200、250℃, respectively, for 30min. Their grain size increases with increasing annealing temperature. When annealing temperature reaches 250℃, uniformed static recrystalled grains can be observed, especially in specimens with 90% rolling reduction whose grain size is less than 10μm which is suitable for superplasticity tests. When Mg-Li alloys are placed under room temperature α-phase will precipitate resulting in a decrease in strength and overaging.
    Table of Content 目 錄
    摘要
    目 錄II
    圖目錄V
    表目錄IXII
    第一章 緒論                1
    1-1 前言                     1
    第二章 文獻回顧                4
    2-1鎂合金的材料特性                4
    2-2 鎂合金的命名規範符號           7
    2-3鎂合金的分類                8
    2-4 合金元素添加對鎂合金性質之影響      9
    2-4-1 添加鋰(Li)               10
    2-4-2添加鋁 (Al)               10
    2-4-3添加鋅 (Zn)               11
    2-4-4添加鈧 (Sc)               11
    2-4-5添加鈹 (Be)               12
    2-5金屬材料再結晶理論          12
    2-5-1 加工硬化               14
    2-5-2鎂合金的熱處理               15
    2-5-3再結晶晶核的形成          16
    2-6鎂合金晶粒細化之方法與理論          16
    2-6-1鎂合金晶粒細化之影響          16
    2-6-2晶粒細化的方法               17
    2-7超輕鎂鋰合金在室溫時效特性之相關研究文獻18
    2-8提升鎂鋰合金強度之相關研究文獻     18
    第三章 實驗方法與設備          30
    3-1實驗材料               30
    3-2 實驗設備               31
    3-3 成份分析               32
    3-4實驗步驟               32
    3-5 冷壓延+熱機處理               32
    3-6 微結構組織               33
    3-6-1 金相觀察(OM)及晶粒大小量測     33
    3-7 XRD測試               34
    3-8 機械性質測試               34
    3-8-1常溫拉伸測試               34
    第四章 結果與討論               43
    4-1 OM顯微組織觀察               43
    4-1-1鎂鋰合金擠製材經3年室溫時效後之金相顯微組織43
    4-1-2 鎂鋰合金擠製材經固溶後之金相顯微組織44
    4-1-3 鎂鋰合金固溶處理後冷壓延之金相顯微組織44
    4-1-4 鎂鋰合金經退火處理後之金相顯微組織45
    4-2 XRD結構分析               46
    4-2-1 擠製材與自然時效3 年後之XRD 分析     46
    4-2-2 固溶處理之XRD 分析          46
    4-2-3 固溶處理後經不同壓延率之XRD 分析     47
    4-2-4 固溶處理加冷壓延後自然時效之XRD 分析47
    4-3 常溫拉伸試驗               48
    4-3-1 鎂鋰合金擠製加固溶後再壓延之機械性質48
    4-3-2 擠製原材與固溶後壓延的自然時效之機械性質49
    4-3-3鎂鋰合金固溶與壓延後的退火之機械性質49
    第五章 結論               69
    參考文獻                    70
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    Advisor
  • Shyong Lee(李雄)
  • Files
  • 963303016.pdf
  • approve immediately
    Date of Submission 2011-05-30

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