Research Of Recrystallization Behavior Of High Purity Copper And Grain Refining Process

With the increasing demand of sputtering efficiency of high purity copper target and uniformity of deposition film in the liquid crystal display industry,the requirements for grain refinement and uniformity of high purity copper sputtering target materials are higher.In this paper,high purity copper target was treated by a four-step test including forging,heat treatment,cold rolling and heat treatment.Thus,the goal of grain refinement and homogenization to optimize the existing technology was achieved by two dynamic recrystallization and static recrystallization.Behavior of high purity copper at high temperature is studied by hot compression deformation test.The result shows when the temperature achieves 500?,obviously behavior of dynamic recrystallization can be observed.When the deformation reaches more than 70%,grain refinement appears to be slow down.As theoretical guidance,a four step process is designed.Firstly,forge at 500? with more than 80% deformation,secondly,heat treatment is carried out with temperature ranging from 200?-310? and holding time ranging from 30 min to 90 min.The third step is unidirectional cold rolling with the deformation controlled at 56%~72%.The last step is secondary heat treatment with the temperature higher than 200? and holding time longer than 60 min.The first process of high purity copper crystal refining consists of two steps,the forging following by heat treatment.Parameters of forging are set to be 500?of temperature and 80% of deformation The grain size refines to 50?m-70?m after forging.The heat treatment is annealing at 210?~310? with holding time ranging from 30 min to 90 min,thus,refines the grain further.The grain size comes to 42.33?m after annealing at 260? with the holding time of 60 min.The standard deviation is 15.51.The secondary process of high purity copper crystal refining,consists of cold rolling and heat treatment.By comparing the different cold rolling deformation of 56%,64%,72% and secondary heat treatment tests,it is found that greater deformation could promote the grain refinement.The average size of copper could be 11?m with 70% of deformation,215? of annealing temperature and 60 min of holding time.In this work,the best process of grain refinement and uniformity of high purity copper is established.The four step process consists of forging,first heat treatment,cool rolling and secondary heat treatment.The process has been applied to industrial LCD copper target developing,and result of 14?m of average grain size and 6 of standard deviation which meets the requirement of the custom,proves the effectiveness of the process.