Effect of Si content on microstructure and properties of automobile aluminum alloy
Different Si doped aluminum alloy materials for automotive use were prepared,and the effects of Si mass fraction on the phase structure,microstructure,hardness,tensile strength,wear performance and wear morphology of the aluminum alloy were studied through XRD,OM,SEM,mechanical performance tests,and friction and wear tests.The results showed that aluminum alloys were mainly composed of α-Al,Mg,Si,as well as the second phase Mg2Si and Mg17Al12.The increase in Si doping mass fraction refined the coral like structure α-Al phase,and the second phase mainly precipitated at grain boundaries.With the increase of Si do-ping mass fraction,the tensile strength and hardness of aluminum alloy first increased and then decreased,the yield strength continued increasing,and the fracture elongation continued decreasing.The tensile strength of a-luminum alloy with a Si doping mass fraction of 3％reached a maximum value of 264.8 MPa,corresponding to a yield strength of 189.6 MPa,a maximum hardness of 58.8 HV,and a corresponding fracture elongation of 10.6％.The wear test results showed that both the wear amount and friction coefficient showed a trend of first de-creasing and then increasing with the increase of Si doping mass fraction.When the Si doping mass fraction was 3％,the friction coefficient and wear amount of the aluminum alloy reached the lowest values,which were 0.052 and 64.8 mg,respectively.The wear resistance of the aluminum alloy was the best,and the direction of the plow groove in the wear surface was uniform and consistent.
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