Effect of Warm Crossing Rolling on the Microstructure, Texture and Annealing Behavior of High-Purity Tantalum

Abstract

With advanced integrated circuit semiconductor chips, the uniformity of microstructure and texture is increasingly required for tantalum (Ta) targets. A combination of warm rolling and 135° cross rolling (CR) at the temperature of 500 °C and 800 °C, i.e., warm cross rolling (WCR), was carried out in tantalum (Ta) plates to investigate the evolution of deformed microstructure and texture. Subsequently, these rolled samples were annealed to analyze the recrystallized microstructure. Results exhibited that WCR samples formed a relatively uniform and weak texture distribution along the thickness direction. The reduction in the proportion of low-angle grain boundaries (LAGBs) was associated with the lower Peierls stresses to be overcome for dislocation motion due to thermal activation in the WCR sample. High grain boundary energy was observed in WCR samples, and WCR can promote dynamic recovery of samples to produce sub-crystals (thermodynamically unstable and serving as nuclei for subsequent recrystallization). Fine average grain size and high content of recrystallized grains with random orientation were obtained after annealing in the WCR sample. This study will provide a theoretical reference for the precise optimization of tantalum process parameters and the improvement in the target material’s performance.

Evolution of Microstructure and Crystallographic Texture in Deformed and Annealed BCC Metals and Alloys: A Review

“…The density of SBs in grains B and D was higher (as can be seen in respective IQ maps) compared to that in grains A and C (Figure 7a,c), and the misorientation of dislocation boundaries in grains B and D reached approximately 4° [88]. cross-rolling at 20 °C, (f,f1) cross-rolling at 500 °C and (g,g1) cross-rolling at 800 °C [84]). Note: IPF color map in (e) is applicable for the IPF maps in (d,f,g).…”

“…In both ASR samples, a uniform distribution of the microstructure throughout the thickness was observed [83]. The study on the 70% warm rolling (UDR and cross rolled at 800 • C) of Ta is reported [84]. In the near-surface region of the samples, the predominant grain orientations were {110}<uvw> and {100}<uvw> (Figure 6d-g).…”

“…IPF maps of 80% deformed Ta processed through (a) symmetric rolling, (b) asymmetric rolling (speed ratio 1.1), and (c) asymmetric rolling (speed ratio 1.2) [83]. (d-g) IPF and (d1-g1) ODF sections (φ2 = 45°) of the near-surface region of Ta, 70% deformed via (d,d1) UDR at 800 °C, (e,e1) cross-rolling at 20 °C, (f,f1) cross-rolling at 500 °C and (g,g1) cross-rolling at 800 °C[84]). Note: IPF color map in (e) is applicable for the IPF maps in (d,f,g).…”