Mg-9Li與Mg-9Li-1Zn合金之加工性及腐蝕性研究

本研究藉由示差掃瞄熱卡計 (DSC)、光學顯微鏡(OM)、掃瞄式電子顯微鏡 (SEM/EDS)、X光繞射儀(XRD)、高溫拉伸試驗機及電化學極化曲線分析儀，來探討鎂-9wt. %鋰(L9)和鎂-9 wt. %鋰-1wt. %鋅(LZ91)合金之高低溫拉伸性質與腐蝕性質。研究結果顯示L9和LZ91鎂合金室溫之拉伸強度範圍僅約在120-140MPa，遠低於一般結構用金屬之強度。氧化試驗顯示鎂-鋰合金會有兩種氧化物生成: 一種為顆粒較細且富黏著性之MgO，另一種為顆粒較大之Li2O2且其含量在LZ91鎂合金比L9鎂合金多。不論在自來水或3.5% NaCl溶液中，LZ91鎂合金所量測到之電流密度皆低於L9鎂合金。在鎂-9 wt. %鋰合金中所添加之1wt. %鋅來增加其抗蝕性，主要歸功於其合金化效應來減少Gibbs自由能，進而降低合金中之反應速率(i.e.腐蝕電流密度)。

關鍵字

鎂-9wt. %鋰合金；鎂-9 wt. %鋰-1wt. %鋅合金；機械性質；極化曲線；浸泡試驗；氧化試驗

並列摘要

In this study room temperature and elevated temperature tensile properties and corrosion properties in Mg-9 wt. % Li (L9) and Mg-9 wt. % Li-1 wt. % Zn (LZ91) alloys are investigated by using DSC, OM, SEM/EDS, XRD, elevated temperature tensile tester and potentio-dynamic polarization. The results showed that the room temperature tensile strengths of L9 and LZ91 alloys are in the range of 120-140 MPa, which can hardly be qualified for structural applications. Oxidation test showed that there are two types of oxides formed on the Mg-Li alloys: fine cohesive granular oxide of MgO and coarse particle-like oxide of Li2O2, and that the amount of coarse particle-like Li2O2 was found to be greater in the LZ91 alloy than in the L9 alloy. The corrosion current densities of LZ91 alloy tested in both the tap water and the 3.5% NaCl solution are lower than those of L9 alloy tested under the same electrolytes. The improvement of corrosion resistance in Mg-9%Li alloy by addition of 1% Zn is attributed mainly to an alloying effect to decrease the Gibbs free energy of the alloy and to, consequently, reduce the reaction rate (i.e. the corrosion current density) in the alloy.

並列關鍵字

Mg-9 wt. % Li-1 wt. % Zn ； Mechanical properties ； Polarization curve ； Immersion test ； Mg-9 wt. % Li ； Oxidation test

參考文獻

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國際替代計量

Mg-9Li與Mg-9Li-1Zn合金之加工性及腐蝕性研究

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