| With the development of new science and technology,the industrial field has made rapid progress,among which Cu and Cu-based materials have become the current important materials.Because Cu-Cr-Zr alloy has high strength and high electrical conductivity,so it becomes a hot product in the application field.But Cu-Cr-Zr alloy has the disadvantages of insufficient electrical conductivity,which is difficult to cope with the practical industrial application.Therefore,in the field of non-ferrous metal materials,solving the imbalance between strength and electrical conductivity of Cu-Cr-Zr alloy has become the key issues to be broken through.Taking Cu-1.0Cr-0.1Zr(wt%)alloy as the research object.This paper proposed two different composite processes of(1)Equal-Channel Angular Pressing(ECAP)+ Deep Cryogenic Treatment(DCT)+ Aging Treatment and(2)continuous Equal-Channel Angular Pressing(ECAP-Conform)+DCT+ Aging Treatment,The effects of ECAP,ECAP-Conform deformation passes,DCT treatment holding time and Aging Treatment on the microstructure and properties of Cu-Cr-Zr alloy were compared and analyzed,and the microstructure mechanism of strength and electrical conductivity improvement of Cu-Cr-Zr alloy was studied.(1)After DCT treatment,the grain size of Cu-Cr-Zr alloy was refined from solid solution state of 55?m to 49?m,and a large number of twin structures appeared,and Cr and Zr phase particles were precipitated.The vacancy concentration decreased,the size of precipitated phase was stable,After DCT treatment(12h),the dislocations accumulated at grain boundaries and inside grains,showing black reticular or flocculent structures,and the dislocation density increased.and the mechanical properties and electrical conductivity were improved.After DCT 12 h,the microhardness,tensile strength,elongation at break and electrical conductivity were 98.6HV,231.1MPa,43.2% and 32.8%IACS,respectively.(2)With the increase of ECAP(1,2,4P)extrusion passes,the grain size of Cu-Cr-Zr alloy was significantly refined,and the deformation band was continuously elongated into lamellar shape.The grain size of Cu-Cr-Zr alloy was about 295 nm by ECAP(4P).After DCT treatment,the grains were further refined to 270 nm,and fine and dispersed Cr and Zr phase particles were precipitated.The microhardness,tensile strength,elongation at break and electrical conductivity of ECAP(4P)+DCT treatment(12h)were 175.2HV,491.0MPa,18.6% and 30.4%IACS,respectively.(3)After three passes of ECAP-Conform,the grain size was refined from 55?m in solid solution state to 283 nm,The grain size is effectively refined at the grain boundary and the entanglement plugs within the grain boundary accumulate high density dislocations.This defect is of great help to the improvement of the mechanical properties of materials.the microhardness reached 154.6HV,the tensile strength and elongation at break were 420.3MPa and 19.0% respectively,and the electrical conductivity was 32.9%IACS.After ECAP-Conform(3P)+DCT treatment(4h),the grain size of the sample was about 262 nm,the microhardness,tensile strength,elongation at break and electrical conductivity were 171.2HV,440.5MPa,19.4% and 35.8%IACS,respectively.(4)The aging treatment promotes the precipitation of the second phase particles,and the mechanical properties were greatly improved through the pinning dislocation.at this time,the internal defects of the alloy were reduced,the scattering of electrons was reduced,and the electrical conductivity of the material was improved.After ECAP(4P)+DCT(12h)+ AT peak(450?×1h),the microhardness,tensile strength,elongation at break and electrical conductivity were 219.9HV,561.6MPa,18.5% and 83.5%IACS,respectively.After ECAP-Conform(3P)+DCT(4h)+ AT peak(475?×1h),the microhardness,tensile strength,elongation at break and electrical conductivity were 208.1HV,489.1MPa,18.3% and 81.2%IACS,respectively. |
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