Study On Microstructure And Properties Of Newly-Developed Cu-Te Based Alloys

Copper-tellurium alloy is of significance for research for its good electrical and thermal conductivity,excellent cutting performance and processing susceptibility.Especially its excellent arc resistance under high current density makes it one of candidates for Cu alloys used for EVs.However,the alloy has a low strength,which limits its further applications in the field of EVs.It is urgent to develop new high-performance tellurium-copper alloys on the basis of existing tellurium-copper alloys,which have enhanced strength as well as excellent electrical conductivity and arc resistance.In order to meet the urgent demands for high-strength,high-conductivity and good arc resistance copper alloys in the field of EVs,this paper develops Cu-Cr-Te alloys,investiates the effects of different heat treatments on the microstructure and properties of the alloys,discusses the effect of precipitation evolution during heat treatment on the alloy properties,and proposed a new testing method for the characterization of the anti-arc ablation performance of the alloys under the condition of frictional arcing.Comparative study is also carried out.The paper provides a new idea and method for the development of copper alloys suitable for EVs.The main findings are as follows:(1)A strong interaction between Cr and Te has been inspected in the alloy during solid solution treatment,leading to growth of Cr-rich phase at elevated temperatures.The interaction between Cr and Te can be suppressed by reducing solution time.By optimizing the solution treatment and aging,the alloy achieves a maximum hardness of 150 HV and an electrical conductivity of 79 %IACS after50% deformation and 3 h aging at 450 ℃.After aged at 450 ℃,the amount of precipitates increases,and the Cr-rich precipitation phase tends to precipitate on the grain boundary.(2)By studying the microstructure and properties of Cu-0.7Cr-0.5Te alloy after heat treatment with increasing deformation amount,combined effect of deformation strengthening and precipitation strengthening can improve the properties of the alloy.The properties of the alloy samples that were solid solution at 950 ℃ for 10 min and cold drawn at 70%-450 ℃ for 1 h reached 143.9 HV and78.6 %IACS.Through the comparative study of different aging conditions,it was found that the hardness and electrical conductivity of the cold-drawn alloy reached the maximum value of 132.1 HV and 84.3 %IACS when aged at 450 ℃for 60 min.(3)The ablation resistance of the tellurium-copper alloy increases with the increase of the Te content.The Cu-Cr-Te alloy after adding Cr has better ablation resistance than the tellurium-copper alloy of the same composition.The better the ablation performance.