Achieving High Yield Strength and Ductility in As-Extruded Mg-0.5Sr Alloy by High Mn–Alloying

Abstract

The effect of Mn on the microstructure and mechanical properties of as-extruded Mg-0.5Sr alloy were discussed in this work. The results showed that high Mn alloying (2 wt.%) could significantly improve the mechanical properties of the alloys, namely, the tensile and compressive yield strength. The grain size of as-extruded Mg-0.5Sr alloys significantly was refined from 2.78 μm to 1.15 μm due to the pinning effect by fine α-Mn precipitates during the extrusion. Moreover we showed that the tensile yield strength and the compressive yield strength of Mg-0.5Sr-2Mn alloy were 32 and 40 percent age higher than those of Mg-0.5Sr alloy, respectively. Moreover, the strain hardening behaviors of the Mg-0.5Sr-2Mn alloy were discussed, which proved that a large number of small grains and texture have an important role in improving mechanical properties.

Role of Al in the Solution Strengthening of Mg–Al Binary Alloys

“…The phenomenon reveals that some locations of Mg have been taken up by smaller atoms (Al), which leads to the change in the crystalline structure. As is known to all, lattice distortion will affect the properties of Mg alloys, such as the improvement of yield strength [29,30].…”

“…In other words, the solid solution of Al has a favorable effect on mechanical properties of pure Mg. Strong basal texture of Mg alloys leads to higher tensile yield strength due to the activity of basal slip, which requires higher shear stress [31][32][33]. On the contrary, some alloying elements [30,31], such as Al can weaken basal texture based on Figure 7. Generally, if tension stress along the extrusion direction is applied on the samples as investigated in this paper, basal slip of Mg-Al alloys will be prone to be activated compared with Mg, then Mg-Al alloys would suffer a loss of yield strength.…”