Synergistic strengthening driven by boundary-dislocation architectures in hot-rolled NiV7 alloy

Single-phase NiV7 alloy plates were hot-rolled at 900 °C, 1050 °C and 1200 °C, respectively. Electron-backscatter diffraction (EBSD) analyses reveal that elevating the rolling temperature enlarges the average grain size from 18.2 μm to 32.5 μm and promotes the development of strong crystallographic texture as well as abundant annealing twins. The geometrically necessary dislocation (GND) density decreases from 1.16 × 10¹⁵ m⁻² at 900 °C to 0.82 × 10¹⁵ m⁻² at 1200 °C, and the substructure increased from 40.5 % to 77.2 %, indicating a significant dynamic recovery. Consistent with these microstructural changes, the ultimate tensile strength drops from 796.9 MPa to 575.1 MPa, whereas total elongation increases from 21 % to 30 %. Quantitative assessment of Hall-Petch, twin-boundary and dislocation-strengthening contributions demonstrates that an optimal strength-ductility synergy can be attained by adjusting the hot-rolling temperature to balance grain size, twin density and dislocation content. This study provides important guidance for the design and fabrication of high-performance nickel-vanadium sputtering targets for advanced thin film applications.