A Study on the Deformation and Corrosion Behavior in Mg-9Li and Mg-9Li-1Zn Alloys

• Main Authors: Hsin-yi Chen, 陳信一
• Other Authors: Chih-fu Yang
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/12957158709077626619

碩士 === 大同大學 === 材料工程學系(所) === 94 === 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.