The Effects Of Zr Content On The Microstructure And Properties Of Cu-Y Alloy

Cu-Zr alloy has excellent mechanical properties and electrical conductivity.The addition of rare earth elements in the Cu-Zr alloy can improve the overall performance of the alloy.When Cu-Y-Zr alloy is in service,high temperature and short-term working conditions will occur,so its stress relaxation resistance performance needs to be further evaluated.Therefore,based on thermal simulation experiments and stress relaxation experiments,combined with the structure and mechanical properties of the alloy,the hot workability and stress relaxation properties of Cu-Y-Zr alloys with different Zr content were studied,and the influence and mechanism of the changes in Zr content were also anlysied.The main conclusions are as follows:（1）The constitutive model of Cu-Y-Zr alloy was constructed.The hot deformation activation energys of Cu-Y-Zr alloys were calculated.The Cu-0.43Y-0.043Zr alloy is203.36)/8)7),the Cu-0.39Y-0.075Zr alloy is 205.6 k/8)7),and the Cu-0.42Y-0.13Zr alloy is 208.9 k/8)7).The increase of Zr content can increase the thermal activation energy of the alloy and inhibit the dynamic recrystallization.（2）The thermal processing map showed that the safe processing zone of the Cu-0.43Y-0.043Zr alloy is that the temperature is 750～830℃,the strain rate is 1～10 s^-1.The safe processing zone of the Cu-0.39Y-0.075Zr alloy is that the temperature is 830～890℃,the strain rate is 2～10 s^-1.The safe processing zone of the Cu-Y-0.13Zr alloy is that the temperature is 750～880℃,the strain rate is 1～10 s^-1.The increase of Zr content can improve the hot workability of Cu-Y-Zr alloy and expand the safe area.The processing safety area of the alloy was small,and the hot workability of the alloy is poor.When the temperature is900℃,a large amount of Zr and Y elements segregated at the cracks causing the alloy cracking.（3）After the solution treatment of Cu-Y-Zr alloy,the electrical conductivity of the alloys did not change much.The electrical conductivity of Cu-0.43Y-0.043Zr alloy is 90%IACS,the electrical conductivity of Cu-0.42Y-0.075Zr alloy is 75%IACS and the electrical conductivity of Cu-0.42Y-0.13Zr alloy is 72%IACS.The increase of Zr element content will obviously reduce the electrical conductivity of the alloy.After aging treatment,precipitates containing Zr and Y elements were found in Cu-0.39Y-0.075Zr and Cu-Y-0.13Zr alloys.The precipitation strengthening effect increased the strength of the alloy.（4）After solution 900℃×1h-cold deformation 80%-aging 400℃×0.5 h treatment,Cu-0.39Y-0.075Zr alloy has the best stress relaxation resistance performance,while Cu-Y-0.13Zr alloy has the worst.The stress relaxation limit stresses of the alloys were calculated.The Cu-0.43Y-0.043Zr alloy is 187.64 MPa,the Cu-0.39Y-0.075Zr alloy is 192.72MPa,and the Cu-0.42Y-0.13Zr alloy is 182.35 MPa.The main factors affecting the stress relaxation performance of Cu-Y-Zr alloys are twins and precipitated phases,among which twins have a greater effect on improving the stress relaxation resistance of the alloy.In this research,the Cu-Y-Zr alloy with a Zr content of 0.075 wt.%has the best stress relaxation resistance performance.