Effect Of Aging Treatment On Microstructure And Properties Of The Rapid Solidification Cu-Ni-Si Alloy

The Cu-Ni-Si based alloys attracted researchers’ attention as high strength and medium conductivity lead frame material used in large scale integrated circuit. The Cu-Ni-Si based alloys have been fabricated mainly using the heat treatment method, the ingot casting mechanical processing method, the mechanical alloying method and the artificial composite method, etc.In this paper, the Cu-Ni-Si based alloy ribbons with different content of Ni and Si were prepared by the arc melting and single roller spinning rapid solidification, in which the rapid solidification technology have been applied in fabricating the Cu-Cr, Cu-Zr and Cu-B alloys successful.The electrical conductivity and mechanical properties of ribbons affected by the content of Ni were discussed. The microstructure and its evolution during ribbons solidification with various solidification rate were investigated. The electrical conductivity and mechanical properties of ribbons prepared at different solidification rate were compared. The microstructure of ribbons heat treated at various aging temperature and time were observed. The electrical conductivity, strength and micro-hardness of the ribbons after heat treated at various aging temperature and time were studied. The precipitate phase transformation dynamics equation and relational expression of electrical at different aging temperature were established, based on the Avrami equation and the principle of phase transformation dynamics.The experimental results show that the micro-hardness and tensile strength of the ribbons increase significantly after aging treatment, while the electrical conductivity of the ribbons restore. A longer aging time, a higher electrical conductivity the ribbons have, especially that aging for 120 min, a rapid upward appears on the electrical conductivity of the ribbons, afterward trend to gradual. While the micro-hardness and tensile strength fall after reach the peak value. The micro-hardness and tensile strength decrease with the increase of aging temperature.The electrical conductivity, tensile strength and micro-hardness of Cu-3.2Ni-0.7Si and Cu-2.8Ni-0.7Si alloy ribbons aging at the optimal process reached the project goals. The electrical conductivity, tensile strength and micro-hardness of Cu-3.2Ni-0.7Si alloy ribbons after fabricating at 2700 r/min and aging at 550 ℃ for 60 min reached optimal, they were 48.56% IACS, 660.6 MPa, 207.6 HV, respectively; The electrical conductivity, tensile strength and micro-hardness of Cu-2.8Ni-0.7Si alloy ribbons after fabricating at 2400 r/min and aging at 550 ℃ for 60 min reached optimal, they were 48.10% IACS, 685.9 MPa, 206.1 HV, respectively.