| High entropy alloy is a kind of multi-component alloy with equal or near equal mol-ar ratio.A large number of experiments have laid a foundation for the study of high en-tropy alloy.However,the exploration of its phase structure and strengthening reasons fro-m the microscale is still in the primary stage.In order to prepare high entropy alloys,a-nd to guide composition design and predict properties through micro scalecalculation,Cr F-e Ni Si Alx(X=0.3,0.4,0.5…2.0)alloys were prepared by laser cladding.The intrinsic state parameters of the alloys were calculated,including mixing entropy?Smix,mixing enthalpy?Hmix,atomic radius difference?,thermodynamic parameter?,valence electron concentr-ation VEC.It can provide guidance for the establishment of the model infirst principle calculation,and provide reference for the phase detection results in the experiment.The virtual lattice approximation(VCA)method was used to calculate the first principles of t-he alloy by CASTEP software package in Materials Studio software platform.Combined with the calculation results of the intrinsic state,the body centered cubic structure mode-l was established to study the density?,lattice constant,Cauchy pressure,Young's mod-ulus E,bulk modulus B,shear modulus G,Poisson's ratio?.The results can provide ref-erence for the hardness and wear resistance test results;when X=0.5,1.0,1.5 and 2.0,t-he phase and microstructure of the alloy were characterized by X-ray diffraction(XRD),o-ptical microscope(OM),scanning electron microscope(SEM)and energy dispersive spec-trometer(EDS).The hardness and wear resistance of the alloy at room temperature wer-e studied by Vickers hardness tester and abrasive wear machine,and consistency betwee-n the test results and the calculation results was analyzed,the results show that:(1)According to the calculation results of the intrinsic state of the alloy,?Smixreaches an extreme value of 13.38 k J/mol at X=1.0;with the increase of the molar content of Al element,when?Hmixis negative,its absolute value becomes smaller,and when X=0.3,?Hmix=-30.40k J/mol,X=2.0,?Hmix=-27.34 k J/mol;the maximum value of atomic radius difference is 5.68%at X=2.0;thermodynamic parameters?more than 1.1,which is in accordance with the solid solution formation conditions;when X=0.3,the valence electron concentration reaches the extreme value of 6.72,and the alloy is dominated by BCC structure.(2)According to the calculation results of Materials Studio,the lattice constant of the alloy increases with the increase of Al mole ratio;the density decreases with the increase of Al;the mechanical properties are stable when the molar ratio of Al is 0.3,0.8,1.5 and 1.8;the Cauchy pressure decreases with the increase of Al content;the values of Young's modulus E,bulk modulus B and shear modulus G decrease with the increase of Al mole ratio,indicating that the strength of the alloy decreases with the increase of Al;Poisson's ratio?and the change trend of B/G indicates that the toughness and ductility of high entropy alloy decrease with the increase of Al content;the calculation results of elastic properties of the alloy are abnormal,and the structure should be further optimized;(3)According to the test results,BCC structure is dominant in the alloy,and the content of BCC phase increases with the increase of Al mole ratio,which is consistent with the calculation results of intrinsic state parameters;with the increase of Al content,the microstructure changes from spherical cellular crystal to fishbone dendrite;when X=1.0,the maximum hardness is 775.1HV,and when X=2.0,the minimum hardness is 682.4 HV;when X=0.5,the lowest wear rate is81.75 mg/cm3,and when X=2.0,the maximum wear rate is 97.35 mg/cm3,which is consistent with the trend reflected in the first principle calculation results.There are 31 figures,22 tables and 169 references in this paper. |
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