Механические свойства тантала с различной микроструктурой при высокоскоростном деформировании

The paper presents experimental data on the mechanical behavior of coarse-grained (80 μm) and fine-grained (1-2 μm) tantalum under static, dynamic and shock-wave loadings; the fine-grained tantalum was obtained by cold forging. The data includes σ-e compression diagrams taken in the range of strain rate from 10-3 to 103 s-1, dependences of the relative change in cylinder length on the impact velocity in Taylor impact tests, and time dependences of the free surface velocity in the Ta specimens under shock-wave loading. It is found that decreasing the Ta grain size 80 times changes slightly the strength properties of the material under static and dynamic deformation. Measurements of the free surface velocity in the metal specimens under shock wave loading at ~17 GPa are indicative of a decrease in elastic precursor in the fine-grained tantalum by ~35 % and of an increase in its critical fracture stress by 15-20 % compared to those in the coarse-grained tantalum. A complex strain rate dependence of strength properties of tantalum was revealed. The microstructure of the coarse-grained Ta specimens loaded at a shock wave pressure of 20 -130 GPa with different action times was examined, and the dislocation density and the number of shear bands formed under shock-wave loading were measured.