Study On The Properties And Mechanism Of High-strength Damping Magnesium Alloy

With the development of modern industry, the negative impact of vibration hasbecome increasingly prominent, which especially affects the accuracy of observation andpositioning on spatial structure parts. Magnesium alloys are provided with excellentdamping capacity and good mechanical property. It is significant to develop high-strengthdamping magnesium alloys on lightweight, strengthening and increasing dampingcapacities of aerospace structures.In this paper, the AZ91D magnesium alloy experienced annealing, T4and T6heattreatment and the AZ91D-x%Y alloys, Mg-5xZn-xY-0.6%Zr alloys and SiCp/Mg-0.6%Zrmagnesium matrix composites were prepared, damping and mechanical properties ofwhich were studied, respectively. The results show that the damping behavior of all alloysand composites above can be explained by G-L dislocation model and severalhigh-strength damping magnesium alloys were developed based on the results above.After annealing heat treatment, the content of β-Mg₁₇Al₁₂phase in AZ91Dmagnesium increased and the shape connected into network. The β-Mg₁₇Al₁₂phasedecomposed after T4heat treatment during which the Al atoms soluted into the α-Mgmatrix while separate out as β-Mg₁₇Al₁₂phase at grain boundaries after T6heat treatment.The addition of Y element turned the shape of β-Mg₁₇Al₁₂phase from discontinuousnetwork into extremely fine dispersed particles and acicular Al₄MgY phase formed in thealloy. The Y alloying and heat treatment will increase the content of solute atoms orprecipitation phases, which forms pinning effect on dislocations, leading to degradation ofdamping.The results above show that solute atoms have an adverse effect on damping capacityof magnesium alloys. To reduce the content of solute atoms, the Mg-5xZn-xY-0.6%Zralloys were fabricated. The I-Mg₃YZn₆quasicrystal phase generated in the alloys refinedthe grains further, and increased the tensile properties up to216MPa as well as the numberof phase and interface in the alloys, which at the same time decreased the dampingcapacities due to the increasing number of strong pinning point on dislocations. Theaugment of critical strain of Mg-5xZn-xY-0.6%Zr alloys implied that existence of solute atoms.The SiCp/Mg-0.6%Zr magnesium matrix composites were prepared by stirringcasting method to further avoid the negative influence of solute atoms. The SiC particleshad no obvious refinement effect on matrix alloy but brought in substantial increase inmechanical properties and decrease in damping capacities. In this study, the dampingcapacities of the composites increased with more and bigger SiC particles. Changes indislocation density in the composites resulted from the addition of SiC particles arepredominantly responsible for the damping variation.The Mg-5xZn-xY-0.6%Zr alloys and SiCp/Mg-0.6%Zr magnesium matrixcomposites with both high damping and mechanical properties will have broaderapplication prospects if the process of melting and solidification could be bettercontrolled.