Plastic Deformation And Strengthening & Toughening Of Magnesium Alloy AZ80

As the lightest metallic structural material, magnesium alloys are attractive for many applications because of their high specific strength and good damping characteristics. However, the use of magnesium alloys has been limited due to their poor plasticity and low strength. Deformation and heat treatment can enhance the mechanical properties of magnesium alloys efficiently. If deformation can be coupled with heat treatment, the pontential of strength enhancement will be bigger. AZ80 magnesium alloy was used in this work, which is a typical kind of Mg-Al-Zn wrought magnesium alloys. This work combined Equal Channel Angular Pressing (ECAP) with heat treatment to improve the properties of AZ80 which could promote its utilities. The result stated:1. After ECAP for 8 passes at 280℃, the alloy's yield strength and ultimate tensile strength were 225MPa and 320MPa respectively, higher than that of cast-annealled state for about 125MPa and 215MPa. After ECAP for 8 passes at 360℃, the alloy's yield strength and ultimate tensile strength were 195MPa and 265 respectively, higher than that of cast-annealled state for about 125MPa and 215MPa.2. The procedure of ECAP for 8 passes at 360℃ plus aging treatment at 150℃ was more efficient than the procedure of ECAP for 8 passes at 280℃ plus aging treatment at 150℃ or 200℃ in enhancing the mechanical properties of AZ80. In first procedure, after aging treatment for 12h, the alloy's ultimate tensil strength got maximum value 340MPa and elongation was 24%. Still, after aging treatment for 12h, much lamellar structure discontinuous precipitation of β-phase was observed by using TEM. After aging treatment for 16h, some granule structure continuous precipitation of β-phase was observed.Although this work showed that deformation could be coupled with heat treatment to enhance the mechanical properties of AZ80, the result was not very satisfied. The reason is that the contradiction between deformation requiring low temperature and solution requiring high temperature can't be solved. So, if we want to well couple deformation with heat treatment to enhance the mechanical properties of magnesium alloy, the alloy must...