Effects of strain rate and loading direction on deformation behaviors of the tantalum-tungsten alloys

Tantalum-tungsten alloys exhibit outstanding comprehensive properties, leading to their widespread application in aerospace, nuclear industry, and power fields. The comprehensive investigation was conducted to systematically analyze the mechanical properties and microstructure evolution under different loading strain rates through tensile tests along the rolling direction and transverse direction at room temperature. The X-ray diffraction, electron backscatter diffraction, and transmission electron microscope were performed to investigate the initial microstructure, texture evolution, and fracture behavior. The intrinsic mechanism of anisotropy in tensile deformation behavior was comprehensively discussed based on microstructural evolution. The sample showed higher yield and ultimate tensile strength along the transverse direction than the rolling direction, reaching 914 MPa at the strain rate of 1 x 10-1/s. At both tensile directions, the strength showed noticeable strain rate sensitivity, while the plasticity exhibited a substantial difference with strain rates. Laminar grain boundary arrangement and strain incompatibility during different loading directions are recognized as leading causes of the plasticity difference and delamination cracking phenomenon. Regarding texture evolution, the initial alloy exhibited distinct {100}//ND texture in the cold-rolled Ta-12W alloy. After deformation, the original texture was maintained only at the strain rate of 1 x 10- 1/s along transverse direction, while all other deformation conditions showed significant texture rotation.