The Effect Of Ball Milling On The Microstructure And Mechanical Properties Of CNTs/Al Composites

With the development of our society,traditional metal materials are more and more difficult to meet the needs of people.Aluminum matrix composites reinforced with carbon nanotubes(CNTs/Al)is expected to be light,high strength,corrosion resistance and other excellent performance,has a broad application prospect in aerospace,transportation,sports equipment and other fields,become a research hotspot in recent years.However,the reported CNTs/Al performance has not yet reached expectations.In this paper,carbon nanotubes reinforced aluminum matrix powders were prepared by different ball milling process,and then carbon nanotubes reinforced aluminum matrix composites were prepared by sintering and hot extrusion.Then X-ray diffraction spectrum(XRD),Raman spectroscopy(RM),scanning electron microscopy(SEM),microhardness tester,electronic universal testing machine were used to analyze the microstructure and properties of the composite of different preparation process for to derive a more excellent one.The results were as followed:High energy ball milling method can effectively disperse carbon nanotubes in the metal matrix,and the solution ball milling(SBM)have a better dispersion effect than the dry ball milling(BM).The SBM can reduce the damage of the surface structure of carbon nanotubes,and it can reduce the aluminum particles easily welded for the cooling effect of ethanol.And the solution ball milling has a role in grain refinement,it is also helpful to the fine and uniform microstructure of composite materials,thus it can get more excellent mechanical properties.The tensile strength of solution ball milled samples can reach 201 MPa,which significantly increased compared with the dry grinding process of 160MPa for the same ball miiling time of 6 hrs.Then,the effect of milling time on the microstructure and mechanical properties of the composites was studied by the way of the ball milling,and the transmission electron microscope(TEM)was used to observe the distribution of carbon nanotubes in composites and the interface with the aluminum matrix.Results show:The extension of the milling time can effectively achieve the effect of refining the grain of the matrix,and is helpful to the dispersion of carbon nanotubes in the composite powders,refine the microstructure of composite materials and uniform.However,the long time ball milling will destroy the integrity of the surface structure of carbon nanotubes.The mechanical properties of the composites increase with the increase of ball milling time,the micro Vivtorinox hardness increased from 5 5HV to 74HV,the tensile strength increased from 171 MPa to 221 MPa,but its elongation is with the increase of ball milling time increased first and then decreased.The formation of Al4C3 in composite materials was observed by the high resolution transmission electron microscopy,generate a small amount of Al4C3 can improve the interfacial wettability of carbon nanotubes and the aluminum matrix in a certain extent,it was able to enhance the interfacial bonding between carbon nanotubes and aluminum matrix,which can improve the performance of composite materials.