Cu-Ni-Sn-Si(Zn) Alloys Designed By The Stable Solid Solution Cluster Model

Elastic and conductive Cu alloys are the indispensable materials in high-end instrumentation and electronic components.Cu-Be alloys are the most typical representative that can meet the requirements of most conditions.The requirement of this kind of materials are increasing with the development of technology and the rise of environmental protection consciousness.The disadvantages of Cu-Be alloys are revealed gradually,such as,poor high temperature stress relaxation resistance,low heat conductive stability,large deformation after aging and toxic dust during production.Therefore,it is increasingly urgent to develop other elastic and conductive alloys.Cu-Ni-Sn alloys have attracted increasing attention for the excellent performance and environmentally friendly.In particular,Cu-15Ni-8Sn alloy has a strength of up to 1300MPa and excellent corrosion resistance and prominent wear resistance.However,due to the high content of Sn in Cu-15Ni-8Sn alloy,the segregation during preparation and discontinuous precipitate during aging are extremely easy to occur,which seriously affect the properties.In order to solve the problem of segregation and discontinuous precipitation in Cu-15Ni-8Sn alloy,the composition of the alloy was optimized by the stable solid solution cluster model.Firstly,the clusters of the main phases in Cu-15Ni-8Sn alloy were analyzed.The cluster of DO₂₂ and Cu matrix were taken as two parts of the cluster formula,and a ternary alloy with the cluster formula of{[Cu-Cu₁₂]Cu₃}₄{[Sn-Ni₁₂]Sn₃}was designed.Then,Si and Zn are selected as the fourth element by investigating the solidus-liquidus temperature range and the interaction between Cu,Ni,Sn.Two series of quaternary alloys with the compositions of Cu₈₀Ni₁₅Sn_5-xSi_x?x=0,0.625,1.25,1.875,2.5 at.%?and Cu₈₀Ni₁₅Sn_5-xZn_x?x=0,0.1875,0.375,0.625,1.25,1.875,2.5 at.%?were designed on the basis of ternary cluster formula.The alloys were prepared according to the composition designed,and the microstructure,solidus-liquidus temperature range,hardness,conductivity and high temperature conductive stability were analysed.The results show that the hardness and conductivity of Cu₈₀Ni₁₅Sn₅alloy design by cluster model are higher than that of Cu-Ni-Sn conmmercial alloys under the same treatment condition.The performance of Cu₈₀Ni₁₅Sn_4.375Si_0.625 alloy is basically the same as that of C72900 alloy.When the added Si is in the solution state,the alloy does not sacrifice too much hardness and conductivity,but the segregation and discontinuous precipitation are significantly inhibited,the high temperature stability is also increased.The performance of Cu₈₀Ni₁₅Sn_4.8125Zn_0.1875 alloy with low Zn content is better than that of C72900 alloy even Cu-Be alloys.The effect of Zn on the segregation and microstructure is not as significant as Si,but a small amount of Zn can effectively improve the hardness and maintain a good level of conductivity.This work analyzed the influence of two added elements on the alloy by various test means,and gave the specific indication of the reasonable amount of added elements,which provided the experimental basis and theoretical guidance for the subsequent design and research of multi-element alloy.