Improvement of microstructure and texture homogeneity of tantalum by dynamic plastic deformation and subsequent annealing: Effect of pass number

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 846; p. 143305
• Main Authors: Zhou, Shiyuan, Liu, Shifeng, Wang, Xiaojun, Deng, Chao, Liu, Yahui, Zhang, Zhiqing, Yuan, Xiaoli
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 27.06.2022; Elsevier BV
• Subjects: Annealing; Deformation effects; Dislocation density; Dynamic plastic deformation; Edge dislocations; Electron backscatter diffraction; Grain boundaries; Homogeneity; Internal energy; Microstructure; Misalignment; Pass number; Plastic deformation; Shear bands; Stored energy; Tantalum; Texture; Pass number; Tantalum; Microstructure; Dynamic plastic deformation; Stored energy
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2022.143305

In the paper, tantalum (Ta) samples were processed with one pass (1-pass), two passes (2-pass) and three passes (3-pass) dynamic plastic deformation (DPD). The deformed and annealed microstructures were studied by using multiple characterization techniques, such as electron backscatter diffraction (EBSD) and X-ray diffraction (XRD). Results showed that the yield strength increases from 611.81 MPa at the first DPD to 1055.19 MPa at the third DPD and all samples reached a 70% reduction finally. The deformed samples are mainly composed of {111}( //LD) and {100}( //LD) grains, and the grains are arranged alternately. Meanwhile, numerous micro shear bands (MSBs) appear in {111} grains of the 1-pass sample. In contrast, they are rarely observed in 2-pass and 3-pass samples, and the distribution of low-angle grain boundaries (LAGBs) and kernel average misorientation (KAM) are more uniform than 1-pass samples. Compared with the 1-pass sample, the 3-pass sample exhibits lower geometrically necessary dislocations (GND) density differences between {111} and {100} grains. The relative Schmidt factor (SR) results indicate that the 2-pass and 3-pass sample is more likely to activate multiple slips than the 1-pass sample. The stored energy variance between {111} and {100} grains in deformed samples is significantly weakened after increasing DPD passes, resulting in that microstructure and texture homogeneity after annealing are improved.