| dc.description.abstract | This research probes into the microstructure and mechanical properties on the new ultra light magnesium alloy. Choose the LAZ1110 magnesium alloy (Mg-11%Li-1%Al-0.5%Zn) which have low density and high formability at room temperature research object. Adding Be and Sc elements into Mg-Li alloys. Four Mg-Li alloys; a bare one (LAZ1110), the second with Sc, the third with Be and the fourth with both Sc and Be, but Mg-Li series alloys normally have low strength and poor precipitation hardening effect. Therefore we use the different processes such as extruded/cold rolled, extruded/solid solution treatment, extruded/solid solution treatment/natural aging, and extruded/solid solution treatment /cold rolled. On the one hand, in order to enhance their strengths and work hardening ability by solid solution treatment and cold work. On the other hand, in order to obtain fine grain size on Mg-Li series alloys, making use of plastic deformation such as hot extrusion, cold rolling ect plus TMT (thermo mechanical treatment) technique.
On mechanical properties, show by the experimental result, for the process of extruded/cold rolled, the ultimate tensile strength achieve about 200MPa with 90% rolling. For other process of extruded/solid solution treatment /cold rolled, the plates were solution treated at 350oC for one hour and quenched, then for rolling reduction of 90%, the ultimate tensile strength achieve about 240MPa because solid solution treatment and work hardening effect. Finally, for the process of extruded /solid solution/natural aging, and at room temperature aging, the peak value appears within 20~40 hours, the ultimate tensile strength approximately 250MPa.
On microstructure, show by the experimental result, all the four alloys uniformly found after the process of extruded/solid solution treatment /cold rolled that 30% and 60% rolling reduction then followed by 250oCx30mins annealing, a fine grain structure was obtain, the grain size of the structure is smaller than 10μm.
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