Improved tensile properties of low-temperature and low-speed extruded Mg–χAl–(4.8 − χ)Ca–0.6Mn alloys

In this work, the microstructure and mechanical properties of Mg–Al–Ca–Mn alloys with different Ca/Al ratios (0.2, 0.6 and 1.0) have been investigated. The results showed that with the increase of the Ca/Al ratios, the grain sizes of the alloys were significantly refined, and the morphologies and types of main second phases changed from a block Mg17Al12 phase to a semi-continuous Al2Ca (C15) phase and a continuous network (Mg, Al)2Ca (C36) phase. The extruded Mg–2.4Al–2.4Ca–0.6Mn alloy, which was consisted of dynamically recrystallized grains and undynamically recrystallized regions, possessed outstanding mechanical properties with the yield strength of 335.9 MPa, the ultimate tensile strength of 354.7 MPa and the elongation of 8.4%. This was mainly due to the resultant effects of grain refinement strengthening, secondary phases strengthening, texture strengthening and work hardening.