Study On Compositions Microstructures And Properties Of High Strength And High Conductivity Cu-Cr-Zr-RE Alloy

Two orthogonal experiments of composition and technology have been researched in thispaper. The three composition factors of Cr, Zr, RE and the four process factors of solutiontemperature, deformation, aging temperature and aging time have been analysis by theorthogonal test. And the optimal design on the composition and process have been decidedby the orthogonal experiment. Through the SEM and EBSD, the research on themicrostructure at different deformation quantity, deformation temperature and strain ratelaid the theoretical foundation of the high strength and high conductivity Cu-Cr-Zr-REalloy for industrialized production.The research shows that, in the cast of Cu-Cr-Zr-RE alloy, the Cr-rich phase precipitated asgranular and aggregated as strips in the matrix grain and grain boundaries. The Zr-richphase mainly distribute in copper boundary as Cu5Zr compound and the rare earth elementwas easy to combine with Cu-Zr. The Zr element was added to the alloy cast conductiveperformance influence. The contribution of Cr element on strength was big while theinfluence on conductivity was small. Choice the components of Cu-1.4Cr-0.12Zr-0.02REalloy as the optimal scheme with electrical conductivity70.76IACS%, tensile strength226.698MPa.The Cu-0.2Cr-0.1Zr-0.05RE alloy with a solution temperature of950degree for1hour andin the water has a better microstructures. And while aging at450degree, therecrystallization was begin. Aging for a long time will make the recrystallization nucleationof further expansion. The precipitates can reply to recrystallization inhibition with smalldeformation at Cu-0.2Cr-0.1Zr-0.05RE alloy. When the deformation quantity was increased,the alloy energy increased while the driving force of recrystallization increased, alloymicrohardness decreased obviously. The solid solution effect on the electrical obviouslywhile the strengthening effect of solid solution on the tensile strength is relatively small.Rolling deformation’s influence on the conductivity was small. The increase of agingtemperature and aging time were helpful for the conductivity of the Cu-0.2Cr-0.1Zr-0.05REalloy, but aging recrystallization will reduce the texture and as a result, the strength of thealloy also reduced. The optimal treatment process of the alloy was solid solution at950degree, rolling with80%deformation, aging at450degree for1hour with hardness148.4Hv, electrical conductivity87.05IACS%, tensile strength559.86MPa and elongation 9.02%.With a room temperature rolling deformation, the Cu-Cr-Zr-RE alloy were mainly in the{110}<112> and {112}<111> type texture. With the increase of deformation, the{112}<111> texture reduced and transformed to {110}<112> texture. The misorientation ofthe grains reduced while the quantity of the deformation increased and the major grainboundary type was small angle grain boundary. While under the low temperature rapiddeformation, the Cu-Cr-Zr-RE alloy texture has changed to {110}<001> and {100}<110>texture. With the low temperature deformation increased, the electrical conductivity of thealloy reduced slowly compared to the room temperature, but the effect of deformationstrengthen was not obvious. In the technological process, combining the room temperaturedeformation and low temperature deformation were helpful to get high strength and highconductivity Cu-Cr-Zr-RE alloy.