Optimizing Structure and Mechanical Properties of Al-Mg Alloys

Abstract

Aluminium-Magnesium (Al-Mg) alloys possess a combination of unique properties such as good mechanical strength, ductility and excellent corrosion resistance. Recent developments in optimizing the intermetallic phases, consolidating dispersoids in the structure continue to be the center of focus. However, a gap still exists on the cost-effective methods to enhance mechanical and corrosion properties of alloy system. This study focused on optimizing the structure, texture and mechanical properties of the Al-Mg alloys through optimization of phase compositions using additive elements, hardness, and the application of heat treatment and annealing cycles. The study also investigated the role of trace elements during casting, homogenization and annealing in modification of the microstructures. The pure 99,9wt. % Al, 99,9wt. % Mg and master alloys with trace elements such as Zr, Cr, Mn and Ti were used. The experimental alloys were investigated using SEM, EBSD, XRD, and TEM after strain hardening and homogenization. Three experimental alloys of Al-Mg system: Al-6.4Mg- 0.4Mn-0.2Zr, Al-5.4Mg-0.6Mn-0.3Zr and Al5.1Mg-0.45Mn-0.2Zr-0.25Cr-0.05Ti were prepared and investigated. The measured average values for ultimate tensile strength (UTS) and yield strength (YS) were 445 Mpa and 438.3 Mpa respectively with the average elongation of 6 %. The hardness of the alloys increased at beginning then decreased with homogenization time.