Properties Of Selective Laser Melting Cu And CuCrZr Alloys Based On First Principles

Copper is an important traditional material in industry,with excellent electrical and thermal conductivity and broad application prospects.In the study of CuCr and CuCrZr alloy systems,it was found that the solid solubility of Cr and Zr in the copper matrix is very low.The enhancement of solid solubility of Cr and Zr elements in the copper matrix,improvement of the strength of copper alloys,and preservation of their electrical conductivity have become a hot research topic among scholars and manufacturing enterprises,while ensuring high strength,high conductivity,high ductility,and corrosion resistance of copper alloys.The emergence of selective laser melting(SLM)technology has largely solved the problem of low solid solubility of Cr and Zr elements in copper matrix.However,there is a significant difference in the SLM formability of alloys with different compositions,resulting in high research and development costs.The combination of theoretical calculation and experimental testing can effectively avoid the problems brought by traditional experimental research,and is of great significance for the development of new materials.This paper mainly investigates the mechanical and electrical properties of CuCr and CuCrZr alloys with different Cr contents using the first-principles method.The effects of alloy composition on their properties are analyzed from both macroscopic and atomic levels,in combination with corresponding experimental observations.On the basis of density functional theory,with the help of CASTEP software package,the elastic constants,Debye temperature and mechanical property anisotropy of copper and CuCrZr alloy were calculated.The results show that the calculated value of the lattice constant of pure copper is 3.60554(?),and the error with the experimental value is only0.055.After doping with Cr and Zr elements,the lattice constant of the alloy gradually increases.When the Cr content reaches 2.0 wt.%,it has a maximum value of 3.60702(?).The elastic constants of CuCr and CuCrZr alloys all satisfy the Born mechanical stability criterion,and their lattice structures are stable.The addition of Cr element can improve the bulk modulus of the alloy,and when the Cr element content reaches 2.0 wt.%,it has the maximum value;the G/B values of CuCr and CuCrZr alloys are between 0.29～0.33 and are less than 0.57,and the Poisson’s ratio is between 0.352～0.369 are greater than 0.3,so the alloys calculated in this paper are all plastic.When the Cr content is 2.0 wt.%,the CuCrZr alloy G/B has a maximum value of 0.33.The calculated intrinsic hardness value of Cu is3.45 GPa,the doping of Cr element increases the hardness of copper.The maximum intrinsic hardness of CuCr alloy is 4.15 GPa,the maximum intrinsic hardness of CuCrZr alloy is 4.61 GPa,(010)and(001)three crystal planes have the same degree of anisotropy.The energy band structures,density of states and electrical conductivity of CuCr and CuCrZr alloys were calculated.The results show that:CuCr and CuCrZr alloys have a large number of energy bands passing through the Fermi surface,showing typical metallic characteristics.With the increase of the content of Cr element,the overall density of state moves to the low energy level region,the number of bonding electrons in the low energy level region gradually increases,and the bonding ability of the alloy is enhanced.There is an obvious peak of the density of states in a small range to the left of the Fermi energy level,and electrons can easily pass through the Fermi energy level and enter the space.The calculated value of pure Cu conductivity is 6.2458×10~7 S/m,and the error is 7.59%compared with the experimental value.With the increase of Cr element content,the electrical conductivity of the alloy decreases gradually,and the minimum value is 2.45×10~7S/m.CuCr0.88Zr0.14 alloy samples were prepared by selective laser melting technology,and the morphology,mechanical properties and electrical conductivity of the alloys under different forming processes were detected by means of SEM,XRD,OM and EBSD.Combining the experiments and literature research in this paper,the results show that with the increase of the Cr content,the hardness of the copper-chromium-zirconium alloy gradually increases and the electrical conductivity gradually decreases.The reliability of the calculation results.However,compared with the calculated values,the experimental values are all smaller,which is related to the crystal model used in the calculation.The calculated lattice system is a defect-free model,and the experimental alloy has certain defects,such as dislocations,vacancies,etc.So the theoretical value will be much higher than the actual value.