The Influence Of Deformation And Heat Treatment On Recrystallization Texture And Annealing Twins In Cu-Ni Alloy Substrates

Recently,Cu-Ni alloy has attracted much attention as the most ideal metal substrates material for YBCO coated conductors.At present,Rolling Assisted Biaxial Texture Technology?RABiTS?is the most commonly used method to prepare biaxial texture Cu-Ni alloy substrates.However,it is noteworthy that a certain amount of annealing twins will be generated in the substrates obtained by this method,and the existence of twins can significantly reduce the conductivity of the superconducting baseband.At the same time,superconductivity is closely related to the content and sharpness of cubic texture.So it is of great significance to study the formation mechanism and evolution of cube texture.Therefore,this paper has chosen Cu-Ni alloys with different compositions as the research object.And the evolution of micro-hardness,microstructure and texture during rolling deformation and recrystallization annealing of Cu-Ni alloy substrates has been systematically studied.At the same time,the focus of the research was to analyze the formation and evolution mechanism of annealing twins.The effects of deformation and alloy composition on recrystallization structure and texture were also discussed.The research about the formation kinetics of twins for non-magnetic Cu₅₆Ni₄₄ alloy substrates show that:The evolution of twins is closely related to the migration of grain boundaries and the formation of cube texture.The content of annealing twins gradually increases and eventually tends to be flat with the duration of the annealing time when alloy substrates with different deformation is annealed at a low temperature.The bigger the deformation,the faster the formation rate of annealing twins,but the final stability value is smaller.In addition,the content of annealing twins increases rapidly with the increase of annealing temperature.The time of the annealing twin content reaches its peak value will be shortened.Then the content of annealing twins decreases significantly due to the rapid growth of cubic oriented grains.The research about high temperature annealing of Cu-Ni alloy with different deformation amounts shows that:Increasing the deformation amount and the content of Cu in the alloy is conducive to strengthening the formation of cubic texture when the Cu-Ni alloy with different deformation amounts anneal at high temperature,especially when the deformation amount is more than 90%,the cubic texture will show a leaping growth.With the increase of cubic oriented grains,the contents of large angle grain boundaries and annealed twin grain boundaries decrease gradually.The research about different annealing processes of Cu₅₆Ni₄₄ alloy substrates with large deformation show that:In two-step annealing,the comprehensive performance of the sample increases gradually with the increase of the pre-annealing temperature.But when the temperature is too high,the comprehensive performance after two-step annealing is obviously lower than that after one-step high-temperature annealing.At the same time,with the increase of annealing temperature in the high temperature stage,the cubic texture content increases gradually,but the strength of cubic texture increases first and then decreases.It is found that the best annealing temperature is 1000?in the high temperature stage.