The Effect Of Cold Rolling And Annealing On The Microstructure And Texture Of Erbium Target

Rare-earth thin film is an indispensable key core material for national defense industry such as strategic emerging industries and new generation electronic information.Acting as the raw material,the properties of microstructure uniformity,grain size and the texture of the rare earth metal targets defect the performance of the sputtering film directly.The closepacked hexagonal crystal structure of rare earth's plastic deformation is complex and variable,and the cold plastic deformation process is prone to work hardening and fracture,and grains are prone to grow abnormally at the heat treatment process,which greatly impact the machinability and quality of rare earth targets.Therefore,solving the fracture due to work hardening during cold rolling and abnormal grain growth during heat treatment have become key core technical problems in the preparation of high-purity rare earth metal targets with uniform microstructure.In this paper,we used the combination of cold rolling and intermediate annealing process to overcome the problem of fracture caused by work hardening during cold rolling.The effects of cold rolling deformation,annealing temperature and annealing time on the microstructure and texture of erbium metal targets were studied by EBSD,XRD,SEM,microhardness tester and OM inspection techniques;the evolution of microstructure and texture of erbium metal during cold rolling and heat treatment were revealed,and obtained the optimal annealing process for erbium metal targets with fine and uniform microstructure.The following conclusion can be drawn from present study:(1)The hardness was gradually increased and the grains were gradually broken and refined with the increasing deformation.When the deformation reached to 20%,the hardness increased sharply;the hardness tended to level off after the deformation variable reached 40%and remained around 130 HV,the deformation mechanism was transformed from the synergistic way of twinning and slip to the slip-dominated;when the deformation reached to 60%,the grains were dominated by fine deformed structures,the average grain size was 3.37?m,and the crystal orientation distribution was uniform,but partial recrystallization occurred inside the grain,and the grain work hardening decreased.(2)The initial recrystallization temperature of erbium metal decreased with the increasing cold rolled deformation,when the cold rolled deformation was 30%,40%,50%and 60%,the initial recrystallization temperature was 520?580?,500?540?,480?540?and 460?520?,respectively.(3)Compared with the initial as-cast state,the crystal orientation of(0110)was weakened gradually with increasing deformation;the crystal orientation of(1210)remained unchanged in the beginning deformation stage,then gradually became weakened as the deformation was increased beyond 50%.The preferred orientation of the(1110)was obvious,and there was a tendency to further strengthen.(4)For the 60%cold rolling deformation of Er metal,the average grain size growth was stable,and the grain size and distribution was uniform,and the average grain size was 9.06?m,and suppressed abnormal grain growth after the optimal annealing process of 740?×1 h.(5)For the 60%cold rolling deformation of Er metal,the orientation index of(0001)was further larger than 1,so the preferred orientation was enhanced.While the orientation index of(0110),(1210)and(1110)always remained around 1,so there was no obvious preferred orientation of them.