Synthesis, Microstructure And Properties Of Nano-SiC_p/Al Composites

In order to investigate the effect of nano-particle content on the microstructure,the mechanical properties and the strengthening mechanisms of aluminum matrixcomposite, the aluminum matrix composites reinforced with1-10vol.%nano-SiCparticles were fabricated by powder metallurgy technique. By using SEM, TEM, XRD,Vickers hardness test and tensile test techniques, the high energy ball millingparameters were optimized, the effects of nano-particle content on the microstructure,the mechanical properties and the strengthening mechanisms of the composites weresystemically investigated and analyzed.The investigation of the high energy ball milling process showed that themechanical properties of the composite made in rotate speed of320rpm was better thanthat of200rpm. In the rotate speed of320rpm, both the size of powder particle and thematrix grain reached the minimum after milling for20hours with PCA content of2.5wt.%. The milling parameters were optimized as: rotate speed:320rpm; millingtime:20h; PCA content:2.5wt.%.The study on the microstructure of nano-SiC_p/Al composites showed that the SiCparticle is evenly distributed and there is no serious agglomeration in the matrix. Thesize distribution of SiC particles was in a certain range. The TEM images showed thatthe composite had fine grains, and with the increasing SiC particle content, the grainsize first increased and then decreased. There were very few dislocations in the1vol.%SiC_p/Al composites, and the deformation dislocations increased with the increasingSiC content.According to the tensile test, the tensile strength、yield strength and the elongationof the composites as extrude firstly increased and then reduced with nano-SiC particlecontent increasing. The tensile strength and yield strength reached the maximum withthe value of452MPa and377MPa respectively when the SiC content was7vol.%.Theyare increased310.9%and416.4%compared to the matrix material. When the SiCcontent was7vol.%, the elongation of the composite as extrude reached the top value of10.9%. Annealing treatment had little effect on the strength of SiC/Al composites, butcan effectively improve the ductility. The influence of annealing treatment on the ductility was enhanced with the SiC content decreasing, the elongation of1vol.%SiC/Alcomposite reached15.3%,which had increased56.1%compared to that as extrude.The main strengthening mechanisms of the composites reinforced with differentSiC particle content are fine grain strengthening, CTE strengthening and Orowanstrengthening. For composites reinforced with different SiC particle content, the abovethree strengthening mechanisms play different effect.