Study On Thermal Processing Technology Of La-Ce-Y-Cu Aluminum Alloy Electric Rod

In this paper,material characterization techniques such as TEM,EBSD,SEM and EDS,combined with conductivity and tensile strength tests,were used to systematically study the evolution of microstructures and properties of La-Ce-Y-Cu aluminum alloy electrical rod after rolling treatment at different hot rolling temperatures and isothermal annealing.In order to further explore the influences of hot deformation and cold deformation treatment on the microstructures and properties of materials,the better double stage deformation(cold)aging process and "hot rolling + isothermal annealing" process are compared,and the better deformation heat treatment process is obtained,which provides a theoretical reference for the research and development and application of rare earth aluminum alloy electrical round rod.The research results are on the following:(1)Compared with Al-B electrical pole,the recrystallization initial temperature of La-Ce-Y-Cu aluminum alloy electrical rod has been improved obviously.The mixed addition of the intermediate alloy increased the amount of precipitated phase in the annealing process of the alloy,which led to the strengthening of the nailing effect of the second phase particles on grain boundaries and dislocations,and delayed the recrystallization of the alloy.(2)The samples optimized by two-stage solid solution were hot-rolled under different temperature gradients,and it was found that the hot-rolled samples showed obvious orientation characteristics,and the direction of the crystal [111] was parallel to the direction of the z-axis.With the increase of rolling temperature,the evolution of alloying elements from solid solution state to precipitated state was intensified,and the deformation structure in the alloy was further transformed into deformation substructure.After 150 ℃ hot rolling processing,samples can obtain better conductivity of 58.6% IACS,and the tensile strength may arrive at 168 Mpa.(3)When the hot-rolled sample was annealed at 150℃ and 300℃,it was found that the higher the annealing temperature,the shorter the time required for the conductivity of the material to reach the peak value,and the lower the peak conductivity.Extending the time of the isothermal annealing,the tensile strength declines integrally,and the tensile strength value of the material is significantly higher than 300℃ isothermal annealing treatment after 150℃ isothermal annealing.Alloy by 150 ℃ isothermal annealing 9h,its comprehensive performance is better,conductivity and tensile strengths were 59.6%IACS and 157 Mpa respectively.(4)After the appropriate two-stage deformation aging treatment,the conductivity of the samples reached 58.5% IACS and the tensile strength values were 181 MPa.Comparing the two-stage deformation aging and the "hot rolling + isothermal annealing" process,it is found that the conductivity of the samples after the double-stage deformation aging treatment is slightly lower than the 59.6% IACS of the "hot rolling + isothermal annealing" process,but its tensile strength values of 181 MPa is significantly higher than the latter’s 157 MPa.According to the inverse Fourier transform,it is found that the main precipitation phase after the two-stage deformation aging has a coherent relationship with the aluminum matrix,and the diffraction pattern and the line scan result in the STEM-HADDF mode can further determine that the type of the precipitation phase is θ’ phase.