Development Of High-Strength And High-Conductivity Copper Matrix Composite Reinforced With TiB₂ Particles

Copper matrix composites reinforced with boride particles have been widely used as electrode material,contact material,integrated circuit lead frame material because of their high strength,high electrical conductivity,excellent high temperature,and so on.In this paper,TiB₂/Cu composites were prepared by powder metallurgy and electric-arc melting.The condition of in-situ reaction to prepare TiB₂/Cu by different methods was discussed.Technique parameters of the in-situ reaction and the affection to the microstructures and properties of TiB₂/Cu composites have been studied.The following are some meaningful results:(1).The conditions of alloying by wet bailing with grain alcohol was observed, and the reasons of forming different phase during the in-situ reaction of sintering with the different ingredients were discussed.The results show that:After the bailing, the mixed phases of Cu,TiH_1.924,TiCu₃ were generated.As the theoretical content of TiB₂ increasing,the size of particles was diminished.Three different types of boride were generated after sintering,namely TiB₁₀₀,TiB₂ or TiB₂₅.(2).The best process parameters were suggested:the theoretical content of TiB₂ was 5%;the forming pressure was 800MPa;the sintered temperature was 1273K;the holding time was 4.5h,on which process parameters Cu matrix composite reinforced with TiB₁₀₀ was got.The properties of materials were electrical conductivity: 20.2%IACS;hardness:161Hv.(3).Two kinds of arc furnace melting had been used,namely direct melting of raw materials method and two-step melting method.Direct melting of raw materials meant that the Cu powder,B₄C powder and pure Ti powder were mixed together and put in the electric arc furnaces to be melted directly.Copper matrix composites only reinforced with TiB₂ were prepared.The theoretical content of TiB₂ was 2.5%,the properties of materials which were prepared by arc furnace melting were electrical conductivity:43.9%IACS;hardness:134Hv.(4).Two-step melting method meant that Cu-Ti alloy was prepared firstly,then it were covered with the Cu-B₄C mixed power.At last TiB reinforced the Copper matrix composites were got.Because the reacted interface was come about by two-step melting,the hardness of product showed uneven;the conductivity was very low.(5).The feasibility of TiB₂/Cu composites which was prepared by microwave sintering was discussed.The results show that contrast to traditional sintering technology,microwave sintering technique can reduce the time of sintering,and the hardness of products was much better than traditional technology.But the improvement of properties by microwave sintering was accorded with traditional sintering technology with the increasing of temperature and time.