Effect Of Ce And Yb On The Structure And Properties Of Al-Mg-Si-Cu Alloy

Due to its low density,good formability,corrosion resistance and weldability,Al-Mg-Si-Cu alloy is very suitable for the manufacture of automobile body panels and is a key material for realizing automobile lightweight.Therefore,in this paper,by adjusting and optimizing the alloy composition,the aluminum alloy ingots for experiment were prepared,and after homogenization treatment,extrusion-drawing processing technology,and solution aging process,the performance change law was studied,and with the help of OM,SEM,HADDF-STEM,EDS,Vickers hardness and other analytical testing methods,respectively,studied the effects of the addition of different Ce and Yb content on the microstructure and mechanical properties of Al-Mg-Si-Cu alloys,and explored the effects of rare earth Ce and Yb in Al-Mg-The specific existence form and strengthening mechanism of Si-Cu.The main research conclusions are as follows:(1)Trace elements of Ce and Yb have obvious refining effect on the as-cast grains of Al-Mg-Si-Cu alloy.When the Ce content is 0.4wt.%,the average grain size is about 80?m.The effect is the best.The alloy has the highest Vickers hardness value of 58.8HV.Compared with the base alloy,the Vickers hardness increases by about 14.8%;when the Yb content is0.6wt.%,Al-Mg-Si-Cu alloy casting The effect of state grain refinement is the best.(2)Trace element Ce can significantly improve the comprehensive performance of Al-Mg-Si-Cu alloy.When the Ce content is 0.4wt.%,the comprehensive performance of Al-Mg-Si-Cu alloy after aging at 170?×12h The best performance:the alloy has a tensile strength of 377 MPa,a yield strength of 321 MPa,and an elongation of 19.1%.Compared with the Al-Mg-Si-Cu alloy,it has increased by 22.4%,15.1%,and 21.6%,respectively.(3)The addition of trace element Yb has also significantly improved the overall performance of the Al-Mg-Si-Cu alloy.When the Yb content is 0.6wt.%,the Al-Mg-Si-Cu-0.6Yb alloy is at 170?×15h The comprehensive performance of 15h is the best:the tensile strength of the alloy reaches 358 MPa the yield strength reaches 301 MPa,and the elongation rate is 18.2%,which are increased by 16.2%,7.9%,and 15.9%respectively compared with Al-Mg-Si-Cu alloy.(4)The fracture morphology analysis shows that the fracture modes of the two alloys are ductile fracture,and the fracture dimples of the Al-Mg-Si-Cu alloy are uneven in size,and the depth of the dimples is different;while the Al-Mg-Si-The fracture dimples of Cu-0.4Ce alloy are small and uniform,and the depth of the dimples is relatively uniform.The second phase particles are distributed at the bottom of the dimples.Al-Mg-Si-Cu-0.6Yb alloy has many dimples in the fracture,and is small and uniform.The bottom of the dimples is also distributed with fine second-phase particles.(5)Through the analysis of Al-Mg-Si-Cu-Ce/Yb aging behavior and strengthening mechanism,both Ce and Yb elements form precipitation strengthening phases in the Al-Mg-Si-Cu alloy structure,and Ce elements in the alloy Form Al₈Si Ce and Al₅Ce precipitation strengthening phase,and Yb element will form Al₂Si Yb precipitation strengthening phase in the alloy.