Atomistic Simulation Study on Spall Failure and Damage Evolution in Single-Crystalline Ta at Elevated Temperatures

This investigation utilizes non-equilibrium molecular dynamics (NEMD) simulations to explore shock-induced spallation in single-crystal tantalum across shock velocities of 0.75–4 km/s and initial temperatures from 300 to 2000 K. Two spallation modes emerge: classical spallation for shock velocity below 1.5 km/s, with solid-state reversible Body-Centered Cubic (BCC) to Face-Centered Cubic (FCC) or Hexagonal Close-Packed (HCP) phase transformations and discrete void nucleation-coalescence; micro-spallation for shock velocity above 3.0 km/s, featuring complete shock-induced melting and fragmentation, with a transitional regime (2.0–2.5 km/s) of partial melting. Spall strength decreases monotonically with temperature due to thermal softening. Elevated temperatures delay void nucleation but increase density, expanding spall regions and enhancing structural disorder with reduced BCC recovery. For micro-spallation, melting exacerbates damage, causing smaller voids and intensified atomic ejection, which increases with temperature. Free surface velocity profiles indicate damage: in classical spallation, first drop marks nucleation, and pullback signals spall layers. In micro-spallation, the first drop is irrelevant, but remains valid. Temperature delays pullback signals and weakens Hugoniot Elastic Limit. This study clarifies temperature-shock coupling in Ta spallation, aiding failure prediction in high-temperature shock environments.