Study On Microstructure And Properties Of Two-dimensional Nanocrystalline Aluminum Matrix Composites By LDM

With the advancement of science and technology,materials are used in more severe environments.The traditional aluminum alloys have disadvantages such as insufficient strength and high reflectivity,which are not suitable for new processing techniques.The proposal of aluminum matrix composites allows aluminum alloys to be used in more extreme environments and applied to more advanced technology.In this paper,Zl114A aluminum alloy is used as the matrix,and graphene nanoplates of two-dimensional nanocrystals are selected as the reinforcement.The composite powder was prepared by high-energy ball milling,and the composites was fabricated by laser deposition manufacturing.OM,SEM,TEM,Raman spectroscopy and XRD were used to observe the structure,determine the composition of composites,test the performance of graphene reinforced aluminum matrix composites,and summarize the enhancement mechanism.The research results of the ball milling process show that under the conditions of wet ball milling,the ball-to-battery ratio is 6:1,and the rotating speed is 240r/min intermittently for 15 hours.After ball milling,the surface quality of the composite powder is good without cracking and falling.When the mass fraction reaches 0.1%,some graphene nanosheets will be pinned inside the aluminum powder particles,and the bonding effect is better.The particles remain spherical or nearly spherical after ball milling,which is helpful for the powder feeding effect of laser deposition manufacturing.The grains of the composite material have been refined observed by OM.The uniform distribution of graphene nanosheets can be clearly seen under TEM,which is verified in EDS.There is no peak for aluminum oxide products and compound brittle phases in XRD.Raman spectroscopy shows that the structure of graphene nanosheets has been damaged to a certain extent after high-energy ball milling and LDM forming,that further exfoliated at the same time,and the quality is even better.In terms of performance,the density of the composite materials processed by LDM reached 98.5%,and the density was good.It can be seen from the tensile properties that the strength of the material is increased while the toughness is also improved.Compared with the pure aluminum alloy,the elongation at break is increased by 193.73%,and the strength is 60.7%higher than that of the pure aluminum alloy.The change trend of microhardness and strength is the same,the microhardness is increased by up to 66%.The mechanism of enhancement is summarized by analyzing the composition of the tissue and the performance of the material.