Mechanical properties of Mg-Al-Mn magnesium alloys with low Al content in the as-cast and extruded conditions

The reported works on the Mg-Al-Mn (AM) alloys with low Al contents are scant. As a result, in the present work, the microstructure and mechanical properties of AM20 (Mg-2Al-0.5Mn) and AM21 (Mg-2Al-1Mn) alloys in the as-cast and wrought conditions were studied. Intermetallics of Al8Mn5 and Al2Mn3 were characterized in the former and the latter, respectively. Grain refinement due to aluminum and manganese addition and applying hot extrusion process were discussed. Besides the as-cast condition, the addition of 0.5 wt% Mn was found to be in favor of obtaining a finer grain size in the extruded condition. The enhancements of tensile properties with respect to the observed grain refinement were discussed and a Hall-Petch slope of 290 MPa/mu m(0.)(5) was obtained, which revealed the remarkable effect of Mn.