Effects of Aging Heat Treatment on the Mechanical and Electrical Performance of Cu-8Ni-2Si-0.5W alloy and Cu8Ni2Si0.5W0.5Al2O3 Metal Matrix composite

The Cu8Ni2Si0.5W alloy and Cu8Ni2Si0.5W0.5Al2O3 composite were fabricated by using the stir casting technique and homogenized at 900C for 5 hours, They were hot forged at 900oC, solution treated. subjected to severe plastic deformation (SPD) and thereafter aged under various conditions., Microstructural analysis using optical microscopy (OM)and scanning electron microscope revealed refined and uniform grain distribution. The precipitation behavior observed to significantly contribute to the mechanical properties of both materials. The Cu8Ni2Si0.5W alloy was found to exhibit higher initial ductility (48.5% elongation) when compared to the Cu8Ni2Si0.5W0.5Al2O3 composite (34.2% elongation). Both alloys showed significant decreases in ductility after severe plastic deformation (SPD) and aging due to dislocation density and precipitation strengthening. The Cu8Ni2Si0.5W alloy achieved maximum yield strength of 630 MPa and ultimate tensile strength of 869 MPa after aging at 480°C for 4 hours, outperforming the Cu8Ni2Si0.5W0.5Al2O3 composite, which achieved 588 MPa and 786 MPa under the same conditions. Hardness also increased significantly, with values of 454 BHN for Cu8Ni2Si0.5W and 435 BHN for Cu8Ni2Si0.5W0.5Al2O3. Electrical conductivity decreased after SPD due to increased defect density and electron scattering but improved with aging, reaching 78.1% international annealed copper standard (IACS) for Cu8Ni2Si0.5W and 63.2% IACS for Cu8Ni2Si0.5W0.5Al2O3 after aging at 480°C for 5h. Aging at 480°C for 4h provided the optimal balance of mechanical and electrical properties for both alloys. The novel alloy compositions demonstrated enhanced mechanical and electrical properties, indicating their potential for high-performance applications.