Study On The Microstructure And Properties Of AT620 Magnesium Matrix Composites Reinforced By Carbon Nanotubes And Silicon Carbide

Magnesium and magnesium alloys are widely used in transportation,aerospace,military and 3C equipment manufacturing fields due to their low density and excellent physical and mechanical properties.However,the mechanical properties of magnesium obtained by alloying and cold working deformation are limited,and the corrosion resistance is slightly improved or decreased.The composite material method can improve the mechanical properties of the magnesium alloy while improving the corrosion resistance.In this paper,different content of carbon nanotubes(CNTs),micronized silicon carbide particles(SiCp)and hybrid enhanced AT620 magnesium matrix composites were prepared by powder metallurgy and hot extrusion,through optical microscope,vertical universal material testing machine.For its organization and performance characterization,optical microscopy,vertical universal material testing machine,X-ray,energy spectr?m analyzer and scanning electron microscope are used.The effects of intermediate control agents on the microstructure and properties of the materials were investigated.Then the effects of CNTs and SiC_p content on the density,microstructure,mechanical properties and corrosion resistance of the composites were investigated.And the effects of hybrid ratios on the microstructure and properties of the composites were also explored.The main results are as follows:The density of the hot extruded composite material is up to 99.69%,the macroscopic defect is the least,the compressive strength is 439 MPa,and the elongation is 14.8%,when the content of the intermediate control agent is 0.5 wt%.After the addition of single reinforcement CNTs,the grain size of AT620 magnesium-based composites decreases first and then stabilizes with the increase of content,while the strength increases first and then decreases,the elongation decreases gradually,and the corrosion resistance first Increase after the decrease.As the content of SiC_p single reinforcement increases,the grain size of the composite changes little,the strength first increases and then decreases,the elongation decreases gradually,and the corrosion resistance increases first and then decreases.CNTs+SiC_p hybrid enhancement can further increase the strength of the composite.The hybrid reinforced composites have higher comprehensive mechanical properties,and the analysis shows that a good synergistic enhancement effect is produced,when the content of CNTs is 0.5wt%.Of course,the tensile strength of 1wt%CNTs+1wt%SiCp/AT620composite material reaches 391MPa,elongation is 15.3%,hardness is 150.1HV,which is36%,0.5%and 16.4%higher than the matrix,when the mixing ratio is 1:1.CNTs+SiC_p hybrid reinforced magnesium-based composite material has a pull-out behavior when fractured,and has a function of transmitting load on both sides of the crack.When the hybrid reinforced composite material breaks,SiC_p acts as the main load-bearing load,and CNTs act as load transfer and refine grain,which together produces a synergistic enhancement effect.