Research On The Microstructure And Performance Of Low Beryllium Cu-0.2Be-XCo Alloy During Heat-treatment Process

As a typical aging strengthening copper alloy,beryllium copper has good comprehensive performance of high strength and hardness,excellent electrical conductivity and thermal conductivity,good abrasion resistance,etc.,which is widely used in aerospace,electronic and electrical,daily hardware and many other areas.At present,high beryllium copper alloy(including Be 1.6% ~ 2.1%)is widely investigated and used.However,Beryllium and it's compounds are toxic,and the preparation process is harmful to human and environment.Therefore,it is necessary to reduce the content of beryllium element,but the decrease of beryllium content decreases the mechanical properties of beryllium bronze.By microalloying and heat treatment process control to develop low beryllium copper alloy(including Be 0.2% ~ 0.7%)is very important.In this paper,the dualistic low beryllium Cu-0.2Be alloys were used to study the effect of Co element on microstructure and performance of the as-cast,as-extruded,aging alloys by adding different Co contents(0%,0.5%,1.0%).And optimize the better amount of Co element in the experimental range is 0.5%.The effect of aging temperature and time on the microhardness and electrical conductivity of Cu-0.2Be-0.5Co alloy was studied.The evolution of the characteristic parameters such as morphology,size,and distribution of precipitated phase during aging were revealed.The intrinsic correlation among the volume fraction,electrical conductivity,and the aging time of precipitated phase was explored.In order to further improve the mechanical properties of the alloy,the effect of solid solution + cold deformation + aging deformation heat treatment on the properties and microstructure of Cu-0.2Be-0.5Co alloy was studied,and the better heat treatment parameters were explored.The results show that: 1.The addition of Co element leads to refining the grains,increasing the microhardness and decreasing the electrical conductivity of as-cast and as-extruded of Cu-0.2Be-XCo alloy.The electrical conductivity of Cu-0.2Be alloy was maintained at 55.9~59.8 %IACS,the microhardness was maintained at 95~100 HV.When the aging time is 2 h and above,the comprehensive performance of Cu-0.2Be-0.5Co alloy is better than that of Cu-0.2Be-1.0Co alloy,and the better addition of Co element is 0.5% in the experimental range.2.Under the condition of solution-treated at 950 ? for 1 h and aged at 440~500 ? for different time,tne electrical conductivity and microhardness of Cu-0.2Be-0.5Co alloy increase sharply in the early aging time,then they increase slowly in the middle time,and they tend to be stable in the late time.Under the aging condition of 460 ?×2 h,the precipitated phase of Be12 Co was elliptical and dispersed on the copper.The conductivity and microhardness were 57.1 %IACS and 243 HV.According to the trend of electrical conductivity of Cu-0.2Be-0.5Co alloy at 440~500 ?,the Avrami equation of phase transformation and the electrical conductivity equation of the alloy were constructed.3.The electrical conductivity of Cu-0.2Be-0.5Co alloy decreases with the increase of deformation and the hardness increases with the increase of deformation.The better deformation heat treatment process Cu-0.2Be-0.5Co alloy is 950 ?×1 h solid solution+50% cold deformation+460 ?×2 h aging.Under the condition,the electrical conductivity and microhardness are well matched,and the values are 58.0 %IACS and 285 HV,respectively.