Effect of Al and Mn Content on the Mechanical Properties of Various ECAE Processed Mg-Li-Zn Alloys

Abstract

The equal channel angular extrusion (ECAE) process is an innovative method to refine grain structure; however, it could be highly technical to perform to result in subsequent exotic mechanical properties. This study will demonstrate how easy or difficult of this operation. Yoshida et al. had applied the ECAE process on Mg-10%Li-1%Zn alloy to obtain a max. superplastic elongation of 421%. This paper tries to re-produce it with Mg-11%Li-1%Zn and Mg-9%Li-1%Zn alloys via the same ECAE process. For the 28 specimens having received 4 passes of ECAE, one of them shows a comparable but lesser elongation of 350% under selective temperature of 523 K and strain rate, 1×10−4 s−1, and the corresponding strain rate sensitivity exponent is 0.48. Furthermore, the ECAE process is imposed on three other Mg-Li-Zn alloys containing Al and Mn (Mg-9%Li-1%Zn-0.2%Mn, Mg-9%Li-1%Zn-1%Al-0.2%Mn and Mg-9%Li-3%Al-1%Zn-0.2%Mn), and this investigation is unprecedented. The original justification for this exploration is that Al and Mn addition may strengthen the α and β phases which are the sole micro-constituents of Mg-Li alloys when bearing Li content between 5% to 11%. Indeed, it is so at room temperature as determined by micro-hardness testing. However, high temperature tensile elongation is not benefited.