Microstructure Control And Mechanical Properties Of Al-5% Cu Alloy

With the increasingly serious problems of energy,environment and safety,material lightweight has become a new development direction of transportation,aerospace and other industries.Cast AlCu alloy has become the preferred material for the development of lightweight materials due to its low density,high specific strength,good wear resistance and corrosion resistance.However,the microstructure of cast AlCu alloy has developedα-Al dendrites.The coarse θ-Al2Cu in the alloy results in stress concentration in the alloy,which reduces the mechanical properties of the alloy.In order to improve the mechanical properties of cast AlCu alloy,chemical modification is an effective method to refine α-Al and θ-Al2Cu phases.In this paper,the effect of alloying elements on the microstructure and mechanical properties of AlCu alloy was studiedThe effects of high entropy alloy and rare earth SC on the morphology and size of primary α-Al and θ-Al2Cu phases in Al-5%Cu alloy were studied by optical microscopy,field emission scanning electron microscopy,transmission electron microscopy and X-ray diffraction.The effects of high entropy alloy on the microstructure of Al-5%Cu alloy were studied In order to provide scientific basis and theoretical guidance for industrial application of AlCu alloy,the relationship between microstructure evolution and mechanical properties of gold was studied.(1)The addition of Sc can significantly modify the primary α-Al in Al-5%Cu alloy.The morphology of primary α-Al changes from coarse dendrite to fine equiaxed crystal.When Sc content increased to 0.8%,the average size of primary α-Al decreased from 386 μm to 29.6 μm,which decreased by 92.5%.Sc can also effectively change the morphology of θ-Al2Cu,and its morphology changes from coarse and uneven structure to fine continuous structure.With the increase of Sc content to 0.8%,the yield strength,tensile strength and elongation of Al-5%Cu alloy first increased,and the yield strength,tensile strength and elongation increased by 61.6%,66.8%and 57.2%,respectively.(2)The addition of Sc significantly improved the size of nano alcu phase in Al-5%Cu alloy.With the increase of Sc content,the size of nano AlCu phase decreases,and the length of nano alcu phase decreases from 371.2 μm to 100 μm,and the width from 20 μm to 10 μm.The amount of nano AlCu phase also increased.Through the analysis of TEM,it can be concluded that nano Sc is estimated to be at both ends of nano alcu phase during solidification,which inhibits its growth.Moreover,the small size nano alcu has a good lattice correspondence with the matrix,which can be used as the precursor of A1 growth to refine the grains together with al3sc.(3)The primary α-Al dendrites and θ-Al2Cu can be effectively refined by adding high entropy alloy to Al-5%Cu alloy.The average grain size of primary α-Al in Al-5%Cu alloy decreases from 147.5 μm to 28.4μm.In addition,the morphology of θ-Al2Cu in Al-5%Cu alloy changed from coarse and inhomogeneous lamellar structure to fine uniform distribution.Compared with the unmodified Al-5%Cu alloy,the tensile strength of Al-5%Cu alloy modified by 0.3wt.%high entropy alloy increased by 20.1%from 169mpa to 203 MPa,yield strength increased by 19.7%from 93.6mpa to 112 MPa,and elongation increased by 92.3%from 13%to 25%.