Research On Microstructures And Properties Of Diamond Reinforced Cu-Ni-Si Alloy

Cu-Ni-Si alloy is the main manufacture of the lead frame material.In order to meet the Cu-Ni-Si alloy under different conditions of requirement,through adding ceramic materials or carbon materials into Cu matrix,it can better coordinate strength and conductivity,and prepare high strength,conductive Cu alloy with excellent comprehensive properties.In this paper,diamond reinforced Cu-Ni-Si alloy with diamond as reinforcement and Cu-Ni-Si alloy as matrix is prepared by casting method through introducing diamond into Cu melts by Ti-Si-D reaction wetting.By means of SEM,TEM,XRD and EBSD,the microstructures of the material are analyzed and the reaction process of Ti-Si-D system in Cu melts and later heat treatment process are explored.Meanwhile,the hardness,conductivity,tensile property and thermal conductivity are tested.It is found that the TiC generated by Ti-D reaction will be connected into a network to prevent the dispersion of diamond in Cu melts when the mixed Ti and diamond compacts are added into Cu melts.Through Ti-Si-D system,diamond can be effectively introduced into Cu melts,and the products can be evenly dispersed in Cu melts.In the process of introducing diamond,Ti-Si phase is superior to TiC to form firstly and attaches to the diamond,and then prevents TiC from connecting to the network during the formation and growth of TiC shell.The effects of Ti and Si are not independent,but related to each other.Only when the mass ratio of Ti-Si-D is in the range of 2:（0.83-1.11）:（1-1.25）,the microstructure uniformity of the composite will be better.In the process of Ni introduction,Ti will participate in the reaction between Ni and Si to form Ni₁₆Ti₆Si₇.In the process of the melts solidification,Ni₁₆Ti₆Si₇ will grow into dendrites of different sizes and shapes according to the different cooling rates.The nano-precipitated phases Ni₁₆Ti₆Si₇ can be precipitated on the Cu matrix by the process of hot rolling,solution quenching and aging heat treatment,and the Ni₁₆Ti₆Si₇ can cooperate with Diamond@TiC particles to form a good hybrid reinforcement system.At the same time,it is found that only when the solid solution degree of material is high and the precipitation force is strong enough,the precipitated phase will not show the growth orientation,and then can grow into granules.The performance test shows that the Cu-3.57Ni-1.8Ti-0.85Si-1D composite achieves the peak hardness of 291.1HV after solution at 900℃for 1 hour and aging at 475℃for 6 hours,at this time the conductivity can be maintained at 40%IACS and the tensile strength can be maintained at 702.2MPa,and the yield strength is 600.5MPa,which has a good comprehensive performance.