石墨烯含量对半固态注射成型制备镁基复合材料组织性能的影响OA

Magnesium matrix composites with different graphene nanoplatelet(GNPs)contents were fabricated based on thixomolding technology,and the effects of GNPs content on the microstructure,interfacial structure,and mechanical properties of the composites were systematically investigated.Using AZ91D magnesium alloy as the matrix,composites with GNPs mass fraction of 0.3%,0.6%,and 0.9%were prepared.The grain morphology was observed by optical microscopy,the dispersion state and failure mode of GNPs were char-acterized by scanning electron microscopy,and the interfacial structure between GNPs and the matrix was analyzed by transmission electron microscopy.The results show that an appropriate amount of GNPs sig-nificantly refines the grains.When the GNPs mass fraction increased from 0.3%to 0.6%,the average grain size decreased from 5.5 μm to 3.5 μm.However,when the GNPs mass fraction further increased from 0.6%to 0.9%,the average grain size increased from 3.5 μm to 4.2 μm.In the composite with 0.6%GNPs,the GNPs were uniformly distributed as thin flakes at both grain boundaries and within the grains,and TEM analysis revealed good interfacial bonding with the magnesium matrix.The failure modes of GNPs during fracture were classified into debonding and fracture.During the thixomolding process,the screw shear effectively achieved uniform dispersion of GNPs and prevented agglomeration;meanwhile,the uniformly dispersed GNPs significantly enhanced the mechanical properties of the composite,increasing the ultimate tensile strength by 21.7%.This study reveals the dispersion behavior and interfacial bonding characteristics of GNPs in magnesium matrix composites,providing an experimental basis for the design and fabrication of high-performance magnesium matrix composites.