An Effective Method to Homogenize the Microstructure of High Purity Tantalum in Sputtering Targets

Abstract

In this study, an effective processing method, 135° clock rolling (CR) and subsequent annealing process, was applied on the Ta plate to improve the microstructure and texture homogeneity. A comparative study was carried out on unidirectional rolling (UR) and clock rolling Ta plates, and their microstructure including texture during the recrystallization was characterized via electron backscatter diffracting (EBSD). The results show that the UR and CR sample exhibit different annealing behavior during the recrystallization process, i.e. the recrystallization kinetics is faster for UR sample than that of CR sample. A heating of 1050 °C for 150 min leads to a strong ?-fiber in the UR sample while relatively uniform texture was found in CR sample. Additionally, grains in UR sample are bigger in size than that in CR sample. The stored energy and nucleation mechanisms for deformed matrix with different orientations play a significant role in the microstructure of Ta plates. And the 135° clock rolling and subsequent annealing process presented in this study was an effective method to homogenize the texture and refine the grains of Ta target.