Effect of Ni:Si ratio on microstructure and properties of powder metallurgical Corson alloy

In this study, powder metallurgical Cu-Ni-Si alloys with different Ni:Si ratios are produced by cold pressing sintering (600 MPa, at 950?C for 60 min) and bulk materials are solution annealed at 950?C for 60 min, quenched in water and aged at 450?C for 60 min. A fine distribution of Ni-Si compounds embedded in a netted-free structure is formed in the matrix. Although a conductivity level of at least 22% IACS is achieved in all powder metallurgical alloys, the impurity effect is dominant and a decrease in the conductivity is detected by increasing Ni:Si ratio. However, a slight increase in electrical conductivity is achieved by the precipitation of nickel silicides in the ?-Cu matrix under aging conditions. Increasing Ni:Si ratio directly increases the hardness of the powder metallurgical matrix, and a hardness value of 73 HV0.1 is obtained for the aged alloy having the highest Ni:Si (5:1) ratio.