Microstructure and Properties of Extruded Single and Dual Phase Magnesium-Lithium Alloy
Mg-8.6Li-6.5Zn-1.4Y and Mg-9.6Li-8.9Zn-1.9Y as-cast magnesium-lithium alloys were deformed under the same hot extrusion process.The microstructures,density and mechanical properties of the two magnesium-lithium alloys were studied.The results show that Mg-8.6Li-6.5Zn-1.4Y as-cast alloy was mainly composed of α-Mg phase,β-Li phase and Mg3Zn6Y1 phase,which was(α+β)dual phase magnesium-lithium alloy.Mg-9.6Li-8.9Zn-1.9Y as-cast alloy was mainly composed of β-Li phase and Mg3Zn6 Y1phase,which was β single phase magnesium-lithium alloy.After hot extrusion deformation,α-Mg phase of the dual phase magnesium-lithium alloy deformed in strip shape along the extrusion direction,and in the single phase magnesium-lithium alloy a few of α-Mg phase in small size were formed;Mg3Zn6 Y1 phase in the two alloys broke and was deformed along the extrusion direction.Compared with those of the dual phase alloy,the average grain size of the single phase magnesium-lithium alloy was smaller,and the average size and volume fraction of the second phase(Mg3Zn6Y1,Mg3Zn3Y2,LiMgZn phases)were larger,and the hardness,yield strength and tensile strength were higher,which increased by 2.72％,7.53％and 3.59％,respectively,and the elongation percentage after fracture decreased slightly.
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