合金元素對Mg-9Li合金加工性及腐蝕性之影響

Effect of Alloying Elements Addition on the Mechanical and Corrosion Properties of Mg-9Li Alloys

李明峰(Ming-Feng Li)

指導教授 ： 楊智富

大同大學/工程學院/材料工程學系所/碩士(2007年)

摘要

本研究藉由示差熱分析（DSC）、光學顯微鏡（OM）、掃瞄式電子
顯微鏡/能量散佈光譜分析儀（SEM/EDS）、電子微探儀/X 光射線波長散
佈分析儀（EPMA/WDS）、X 光繞射儀（XRD）、微硬度試驗機、拉伸試
驗機及恆電位儀，來探討Mg-9 wt% Li（L9）、Mg-9 wt% Li-2 wt% Al
（LA92）、Mg-9 wt% Li-2 wt% Al-1 wt% Zn（LAZ921）及Mg-9 wt% Li-2
wt% Al-0.04 wt% Sc（LAS920）四種雙相鎂鋰合金之機械性質與腐蝕性
質。研究結果顯示，經固溶及室溫48 小時＋50℃48 小時二階段時效之
LA92、LAZ921 及LAS920 合金室溫拉伸強度均大於200MPa，已達一
般結構用金屬之強度，若施以60%之輥軋，強度均可大於250MPa，其
中LAZ921 之強度甚至達300MPa 以上。四種鎂鋰合金經300℃、48 小
時之氧化，α相表面生成連續的MgO 氧化皮膜，而β相則生成凸起且
形狀及大小不一之島狀Li2O2 氧化物。於3.5 wt % NaCl 水溶液中所測得
之極化曲線顯示，除了L9 較商用AZ91D 鎂合金有較大的腐蝕速率外，
其餘三種鎂鋰合金之腐蝕電流密度均小於或與商用AZ91D 者相近，顯
示LA92、LAZ921 及LAS920 合金抗蝕性不低於商用之AZ91D 鑄件。

關鍵字

鎂鋰合金 ； 拉伸性質 ； 腐蝕性質 ； 氧化試驗

並列摘要

In this study room temperature mechanical and corrosion properties in
Mg-9 wt% Li (L9), Mg-9 wt% Li-2 wt% Al (LA92), Mg-9 wt% Li- 2wt%
Al-1 wt% Zn (LAZ921) and Mg-9Li-2 wt% Al-0.04 wt% Sc (LAS920)
alloys are investigated by using DSC, OM, SEM/EDS, EPMA/WDS, XRD,
micro-hardness tester, tensile tester and potentiostat. The results showed that
the room temperature tensile strengths of LA92, LAZ921 and LAS920 alloys
are greater than 200 MPa, which are well qualified for structural applications.
After 60% mechanical rollong, their tensile strengths are greater than 250
MPa, and LAZ921 alloy exhibits the highest tensile strength of 314 MPa.
Oxidation test showed that there are two types of oxide formed on the Mg-Li
alloys: a continuous cohesive oxide of MgO on α phase and particle- or
island-like oxides of Li2O2 on β phase. The corrosion current densities of
LA92, LAZ921 and LAS920 alloys tested in the 3.5 wt% NaCl aqueous
solution are lower than a commercial AZ91D alloy tested under the same
electrolytes. But the corrosion current densities of L9 alloy is higher than the AZ91D alloy. Corrosion current densities of LA92, LAZ921 and LAS920
alloys are equal or better than that of AZ91D, indicating that the corrosion
resistance of LA92, LAZ921 and LAS920 are better than AZ91D alloy.

並列關鍵字

Mg-Li alloys ； Tensile properties ； Corrosion behavior ； Oxidation test

參考文獻

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