Optimization of microstructure and properties of as-cast various Si containing Cu-Cr-Zr alloy by experiments and first-principles calculation

The CuCr0.8Zr0.12Six (wt.%, x = 0, 0.02, 0.05 and 0.2) alloys were designed and prepared by casting method. The function mechanism of Si content on as-cast microstructure evolution and properties was revealed with the guidance of thermodynamic analysis and first-principles calculation. Cr3Si tends to form during solidification at higher Si content due to its relatively low excess Gibbs free energy, which was proven to significantly affect the mechanical properties of alloys. The relationship between microstructure and mechanical properties of as-cast CuCr0.8Zr0.12Six alloy was also experimentally investigated. With Si content increasing from 0 to 0.2 wt%, the tensile strength and elongation of the CuCr0.8Zr0.12Six alloys simultaneously increase from 251 MPa to 29.0% in CuCr0.8Zr0.12Si0 to 268 MPa and 33.0% in CuCr0.8Zr0.12Si0.05, and then decrease to 229 MPa and 23.7% in CuCr0.8Zr0.12Si0.2. Simultaneously, the electrical conductivity and hardness of CuCr0.8Zr0.12Si0.05 respectively reach 57.2 %IACS and 85.1 HV, CuCr0.8Zr0.12Si0.05 was thus identified to be the best composition with relatively high comprehensive properties in this case.