Microstructure And Properties Of Cu-Cr-Zr Alloy Strip Processed By Cryogenic Plastic Deformation

Copper and copper alloy strips are widely used in the electronic integrated circuit industry.With the rapid development of the 5G industry,integrated circuit lead frames and high-speed backplane materials require higher tensile strength and conductivity.Cu-Cr-Zr alloys have excellent tensile strength,good electrical conductivity and high temperature stability,and have been widely used in the electronics industry.In order to meet the standard requirements of miniaturization,high performance and integration of 5G industrial products,it is urgent to develop high-strength,high-conductivity Cu-Cr-Zr alloy strips.In this paper,a composite deformation process of equal channel extrusion(ECAP)+ cryogenic rolling(CryoR)is proposed.The influence of the microstructure and properties of the strip was discussed,and the mechanism of alloy strengthening and electrical conductivity was discussed.The main results are as follows:(1)The Cu-Cr-Zr alloys were subjected to room temperature rolling(RR)and low temperature rolling(CryoR)of 50%,75%,90%,and 98%,respectively.The grains are elongated and refined during the RR deformation process,and the grains are broken and refined during the CryoR deformation process,and the dislocation density of the CryoR deformed alloy is higher than that of the RR deformed alloy.A large number of nanotwins were found in the deformed structure of CryoR(98%).The electrical conductivity,microhardness,tensile strength and elongation at break of RR(98%)deformed Cu-Cr-Zr alloy strip are 34.1%IACS,161.8HV,478.9MPa,6.5%,CryoR(98%)The deformed alloys are 30.3%IACS,183.7HV,563.4MPa,and 8.6%,respectively.After vacuum aging treatment,precipitates were produced in both RR and CryoR alloys,but the precipitates in the RR deformed alloy agglomerated at the grain boundaries,resulting in low alloy strength,while the precipitates in the CryoR deformed alloy did not.Phenomenon.The electrical conductivity,microhardness,tensile strength and elongation at break of the aged CryoR(98%)alloy are 81.6%IACS,211.4HV,671.5MPa and 12.4%,respectively.(2)After the Cu-Cr-Zr alloy is compositely deformed by ECAP+RR/CryoR(90%),the grains are continuously refined with the increase of ECAP passes,and the dislocation density increases.The alloy deformed by ECAP+RR(90%)will recover,the grain refinement degree and dislocation density increase slightly,and the effect of performance improvement is not obvious.The electrical conductivity,microhardness,tensile strength,and elongation at break of 4P+CryoR(90%)deformed alloy are 30.4%IACS,190.6HV,618.5MPa,and 12.3%,respectively.After vacuum aging,their properties are 81.4%,respectively.IACS,228.5HV,704.3MPa,15.1%.(3)After the Cu-Cr-Zr alloy undergoes severe plastic deformation of4P+CryoR(98%),the alloy structure contains fine nanotwins,nanocrystals,ultrafine grains and high-density dislocations.The electrical conductivity,microhardness,tensile strength,and elongation at break of the Cu-Cr-Zr alloy strip are 29.2%IACS,204.3HV,628.3MPa,and 9.75%,respectively.After vacuum aging,the properties are 81%IACS,respectively.,233 HV,731MPa,8.5%,which further improved the strength and significantly improved the electrical conductivity.The best preparation process route was ECAP(4P)+CryoR(98%)+ AT(450 ℃ × 0.5h).The high strength of the low-temperature deformed Cu-Cr-Zr alloy is attributed to deformation strengthening,twinning strengthening and precipitation strengthening,and the high electrical conductivity is attributed to the special mechanism of nanotwin boundaries and fine precipitates.