The Effect Of Si And Sn On The Microstructure And Properties Of Cu-Ni-Sn-Si Alloy

In recent years,a large number of instruments and equipment are moving towards the development of the miniaturization,high-performance trends,which not only require electronic components should have a high degree of integration,fast signal transmission speed,but also require its higher performance.Copper-based elastomeric alloys are widely used in the fields of electronic communication,instrumentation,and conductive elasticity in terms of their outstanding electrical conductivity,thermal conductivity and mechanical properties.Among them,Cu-Ni-Sn alloy with its excellent wear resistance,corrosion resistance and good electrical conductivity,thermal stability and other properties were used to manufacture various types of elastic components.However,Cu-Ni-Sn alloy has a low conductivity,usually about 7% ?8% IACS,and when Sn content is high,Sn content is high,Cu-Ni-Sn alloy is prone to serious segregation during solidification,which caused Hot rolling cracking.This will not only affect the processing rate of its processing,but also can not guarantee the uniformity of the performance of the alloy products.Therefore,based on the characteristics of Cu-Ni-Sn and Cu-Ni-Si alloys,this study was conducted to study the Cu-Ni-Sn-Si quaternary alloy with low Sn content and a small amount of Si instead of Sn.In order to obtain good mechanical properties and electrical conductivity,and provide a good theoretical basis for the actual production,the influence of conventional deformation aging and double cold rolling double aging treatment on Cu-Ni-Sn-Si quaternary alloy was discussed,and the optimum process parameters were determined.The main research work and the results are as follows:?1?The developed dendrites are present in the microstructure of the cast Cu-Ni-Sn-Si alloy.The alloy grain was refined,and the segregation phenomenon was improved when adding Si,Sn element.The influence of Si and Sn on the hardness and electrical conductivity of cast alloy is basically the same.With the increase of Si and Sn content,the hardness of the alloy showed a tendency to increase continuously,and its conductivity gradually decreased,but the influence of Si on the microstructure and properties of the alloy was more significant.After the pretreatment aging treatment,the sol atom Sn is still in the form of solid solution in the alloy matrix,and under the same aging conditions,the added Si element will form Ni₂ Si phase with Ni,and quickly precipitate in the aging process.The hardness and conductivity of the alloy were significantly improved,and when the Si content of 1%,the aging effect of the most significant,but when the addition of Si more than 1% will hinder the alloy aging process,so the preferred composition ratio is: 4% Ni,1.5Sn,1% Si.?2?Cast Cu-4Ni-1.5Sn-Si alloy after 70% hot rolling deformation,and then applied 0% to 70% pre-cooling deformation,in the 350 ??500 ?,2h ?8h under the conditions of aging treatment found : Increase the degree of pre-cooling deformation,in the range of 350 ??450 ? can increase the temperature of the alloy aging process to improve the overall performance of the alloy.The optimum aging performance of the alloy is 70% pre-cold deformation,450?×6h aging,and the comprehensive performance can be obtained under the aging process.The hardness and conductivity of the alloy are 269 HB and 26.6% respectively.?3?In order to quantitatively analyze the relationship between the pre-cooled deformation and the precipitation behavior of Ni₂ Si phase in the aging process,the aging kinetics of the Cu-4Ni-1.5Sn-Si alloy were analyzed,When the alloy is 0 ?70% cold rolling deformation,and then aging at 450?,2⁸h.The relationship between the volume fraction f of the precipitated Ni₂ Si phase and the pre-cooling deformation ? is obtained: f= 1-exp???(-0.030*t^0.524+0.410?),and it can be concluded that increasing the degree of precooling deformation can effectively promote the aging process of Cu-4Ni-1.5Sn-Si alloy,thus proving that it can be effective for increasing the precooling deformationimprove the conductivity of goldin theory.?4?In order to further improve the comprehensive properties of the alloy,Cu-4Ni-1.5Sn-Si alloy was subjected to double cold rolling aging treatment,and the alloy is better double cold rolling aging process is 50% cold rolling and then 500?×2h pre-aging treatment,followed by 70% cold rolling alloy,400?×8h secondary aging,in the aging process under the alloy hardness and conductivity can reach 275 HB,33.2% IACS,with the conventional aging process?70% cold rolling,450?×6h aging?contrast alloy hardness and conductivity have been improved,especially the alloy conductivity increased by 24.8%.