Effect of Cr content on microstructure and properties of Cu-Cr-W alloy based on theoretical and experimental analysis

Abstract

Cu-W alloy has been widely applied of is due to the combination of the high melting point and high strength of W metal and the good electrical conductivity of Cu metal. In this study, the first-principles were used to construct Cu-Cr-W alloy models with different Cr ratios, and their electronic structures and elastic constants were calculated. The results show that the introduction of Cr atoms changes the energy of the electron states of Cu-3d and W-5d orbitals, promoting them to couple and form bonds more easily. Moreover, Cr-3d and W-5d orbitals can form strong bonds, resulting in an increase in the bulk modulus, Young's modulus and shear modulus of the material with the increase in the number of Cr atoms. According to this calculation trend, Cu-W alloys with different Cr contents were prepared by mechanical alloying according to the atomic ratio and sintered into billets by SPS to study their structures and properties. Experiments show that when the Cr addition reaches 4 at%, the material has the best strength and hardness. The tensile yield strength is increased by about 34.7% compared with that of the Cu-W alloy, and the tensile strength is increased by about 30.4%. Considering the combination of material strength and electrical conductivity, when the Cr addition is 1–2 at%, the material has both excellent electrical conductivity and tensile strength. In addition, an appropriate amount of Cr can refine the grains. The diffusion of Cr on the surface of W particles to form Cr0.5W0.5 and its own hard characteristics are the main reasons for improving the tensile strength of Cu-Cr-W. By comparing the calculated elastic constants and the experimentally obtained changes in mechanical properties, it is found that the trend of the calculation results can well match the experimental results.