Research On Microstructure And Properties Of Cu-V-Co-Cr-Fe-Ni High-Entropy Alloy In Vacuum Arc Meiting And Powder Metallurg

The concept of high-entropy alloys(HEAs)have received extensive attention since its inception.High-entropy alloy is a new type of alloy composed of five or more metal elements.This alloy has excellent physical properties.Therefore,the study of high-entropy alloys are of great significance in materials science.Numerous studies have shown that high-entropy alloys have many excellent properties,such as wear resistance,high-temperature resistance,corrosion resistance,oxidation resistance,and unique magnetic properties.In this paper,X-ray diffractometer(XRD),scanning electron microscope(SEM),energy dispersive analysis(EDS),and other instruments are used to test and analyze the microstructure and structure of high-entropy alloys.The tensile,compressive,and Vickers hardness of the high-entropy alloys are tested and analyzed by a microhardness tester,and the corrosion resistance of the alloy is analyzed by an electrochemical workstation.The specific research contents are as follows:(1)In this paper,the Cu_xCo Cr Fe Ni(x=0,2,4,6 at.%)high-entropy alloy is prepared by the electric arc furnace melting method.It was found that with the increase of Cu content,the alloy still maintains a single FCC structure from a structural point of view.In terms of mechanical properties,with the increase of Cu content,the fracture mode of the alloy changes from ductile fracture to brittle fracture.When x=0 at.%,the alloy has excellent tensile plasticity.In the tensile test,the deformation of the alloy exceeds 50%.When the content of Cu element reaches 6 at.%,the tensile fracture mechanism of the alloy completely becomes brittle fracture,at the same time,it was found that the yield strength and tensile strength of the alloy increased with the increase of Cu content.When x=4 at.%,the yield strength and tensile strength of the alloy reached the highest,which were188.8 MPa and 439.3 MPa.The electrochemical corrosion performance of the alloy in 1L/M HCl solution was studied,and it was found that the addition of Cu element would reduce the corrosion resistance of the alloy.(2)To study the effect of V on the microstructure and mechanical properties of Cu₄CoCrFeNiV_x(x=0.2,0.4,0.6,0.8 at.%)high-entropy alloys.The study found that the addition of the V element did not change the FCC structure of the alloy,but due to the large difference between the atomic radius of the V element and the atomic radius of other elements,high-entropy alloys have lattice distortion effects.The peak is shifted slightly to the right.When x=0.6 at.%,the mechanical properties of the alloy are the best,the yield strength of the alloy is 190MPa,the tensile strength is 450MPa,and the plastic deformation exceeds 50%.In the electrochemical corrosion performance analysis,it was found that when x=0.2 at.%,the passivation range of the alloy is large,and the self-corrosion current density of the alloy is the lowest,which is 7.9504×10^-4A·cm^-2.(3)Cu₄Co Cr Fe Ni(VC)_x(x=2,4,6,8 at.%)high-entropy alloy was prepared by a combination of powder metallurgy and electric arc furnace melting,and the effects of VC on the microstructure and properties of the alloys were studied.The study found that with the increase of VC content,there would be segregation in the alloy,mainly the enrichment of Cr element and VC.With the increase of VC content,the enrichment becomes more and more obvious,but the distribution in the alloy is very uniform.In the tensile mechanical property test,it was found that cracks and cracks would occur in the Cr and VC-enriched regions during stretching,which will affect the toughness of the alloy.With the increase of VC content,the yield strength,tensile strength,and Vickers hardness of the alloy gradually increased.(4)In this paper,Cu₄Co Cr Fe Ni high-entropy alloys are prepared by powder metallurgy,and their properties are studied by heat treatment at different temperatures.It was found that the metal powder would be alloyed and agglomerated during the ball milling process,and the particle size of the metal powder will gradually decrease with the increase of the ball-milling time.After heat treatment,it was found that the hardness of the alloy increased first and then decreased,and the hardness of the alloy reached the highest at 400?.