Electron‐deposition‐induced spallation in tantalum

摘要

Spallation induced in thin specimens of tantalum by rapid in‐depth energy deposition has been studied in a series of electron‐beam experiments in which peak deposition levels were varied from ∼130 to ∼700 J/g. Incipient spall was observed at ∼225 J/g. Analysis of the experiments with a one‐dimensional wave‐propagation code indicated that the tensile stress at the incipient spall level was ∼26 kbar, which is considerably lower than the ∼70-kbar tensile stress previously found to produce comparable damage in room‐temperature plate‐impact experiments. The analysis further indicated that strains induced in the samples at the incipient spall level were about the same (0.035) for both types of experiments after accounting for the thermal‐expansion component of strain in the electron‐beam experiments. This observation supports a contention that induced mechanical strain would be a suitable criterion for use in describing the spallation phenomenon in uniaxial‐strain situations.