Effect Of ECAP Deformation On Microstructure,Texture And Properties Of ZA63 Alloy

Magnesium alloy has gained obvious advantages in competition with other structural materials due to its light weight,high specific strength/stiffness and other series of advantages,which became a hot spot in the research,development and application of new materials.However,due to its poor high temperature stability and poor heat and corrosion resistance still limit its industrial applications.Mg-Zn-Al（ZA-based）heat-resistant magnesium alloys has attracted widely attention because of its high melting pointτphase(Mg₃₂（Zn,Al）₄₉).It is expected that the high temperature mechanical properties of magnesium alloys will be improved by alloying,thermal deformation and heat treatment.The subject systematically studied the microstructure and mechanical properties of ZA63 alloy under different heat treatment process.The effects of ECAP passes on the microstructure,texture orientation,room temperature tensile properties and damping properties of the alloy were investigated.The microstructure and mechanical properties of ZA63 alloy were studied under different heat treatment processes to determine the optimum heat treatment process parameters:The solution treatment process was 345℃for 40h（water quenching）,the aging process was pre-aging 75℃for 24h and aging175℃for 20h（air cooling）.Aging time have a great influence on the number of precipitated phases and grain size,and the hardness of the aged alloy increased remarkably.The tensile strength and elongation were improved when compared with the as-cast alloy after aging treatment,which were 232MPa and 14.3%,respectively.Compared with the as-cast increased by 34.9%and 43%.The ECAP deformation of ZA63 alloy at 330°C shows that the alloy has the highest comprehensive mechanical properties at 4P.With the ECAP passes increasing,the small average grain size and the high texture intensity makes the alloy exhibit high tensile strength and yield strength.The elongation efficiency increased,due to a new texture with the base plane inclined 45°relative to the extrusion direction over traditional deformation behavior.The damping properties of ECAP deformed specimens were studied.The damping-strain curves of ECAP deformed alloys were linearly independent and linearly related.With the increasing of ECAP passes,the room temperature damping performance was affected by the movable dislocation density and dynamic recrystallization.The investigation of the temperature dependent damping capacity showed that the damping capacity increased when the temperature increased and the frequency increased.There were two distinct internal friction peaks in the damping-temperature spectrum:the P₁ peak around150°C and the P₂ peak around 250³00°C.The P₁ peak was a grain boundary slip resulting in internal friction of the crystal and has a heat activation characteristic.The P₂ peak was related to the energy stored in the material and caused by the recrystallization process.