Plastic deformation behavior of a Cu–10Ta alloy under strong impact loading

Abstract

In this work, a Cu–10Ta alloy with a copper to tantalum mass ratio of 9:1 is prepared using powder metallurgy technology. Physical properties of the alloy, including density, microstructure, melting point, and constant-volume specific heat, are tested. Via the split Hopkinson pressure bar (SHPB) and flyer-plate impact experiments, the relationship between equivalent stress and equivalent plastic strain of the material is studied at temperatures of 298–823 K and under strain rates of 1 × 10−3–5.2 × 103 s−1, and the Hugoniot relationship at impact pressures of 1.46–17.25 GPa and impact velocities of 108–942 m/s is obtained. Evolution of the Cu–10Ta microstructure that occurs during high-strain-rate impact is analyzed. Results indicate that the Cu–10Ta alloy possesses good thermal stability, and at ambient temperatures of up to 50% its melting point, stress softening of less than 15% of the initial strength is observed. A modified J-C constitutive model is employed to accurately predict the variation of yield strength with strain rate. Under strong impact, the copper phase is identified as the primary source of plastic deformation in the Cu–10Ta alloy, while significant deformation of the high-strength tantalum particles is less pronounced. Furthermore, the longitudinal wave speed D is found to correlate linearly with the particle velocity u upon strong impact. Analysis reveals that the sound speed and spallation strength of the alloy increase with increasing impact pressure.