Experimental measurements of the strength of metals approaching the theoretical limit predicted by the equation of state

Abstract

The approach to the ultimate strength of metals is determined experimentally. The ultimate strength of metals was calculated using a realistic wide-range equation of state. The strength of metals was measured using shock waves created in aluminum and copper foils with a short- (20–100 ps) pulse high-power laser. The strength of the materials was determined from the free-surface-velocity time history, which was measured with an optically recording velocity interferometer system. The strain rates in these experiments were in the range (1.5–5)×108 s−1.

Nanovoid nucleation by vacancy aggregation and vacancy-cluster coarsening in high-purity metallic single crystals

“…Figure 11 shows that, for moderate strain rates (∼10 6 s −1 ), the dynamic strength is fairly independent of temperature except close to the melting point, at which point the spall pressure decreases dramatically. 68 Similar conclusions were also obtained from semiempirical equations of state by Moshe et al 69 This strong thermal sensitivity in the high temperature range provides a strong indication that the experimentally observed behavior is in the thermally activated range, which is precisely the range considered in the model. However, as will be shown subsequently, the strain rates considered in these experiments are well below the range of applicability of the model and therefore no direct comparison can be performed with these data.…”

“…At low-to-moderate strain rates (∼10 4 -10 6 s −1 ), the spall strength is observed to be strongly dependent on the microstructure 70 69 from the equation of state is also represented in the figure. and 12). In general, the spall strength increases with increasing grain size, with the maximum spall strength being attained for single crystals.…”

Critical behavior in spallation failure of metals

“…The most widely used experimental methods are plate impact 1 and, more recently, high power pulsed laser shock generators. [2][3][4][5][6] Strain rates up to 10 8 sec Ϫ1 can be achieved with laser shocks, higher than those in plate impact experiments.A complete description of spallation involves understanding and linking processes taking place at very different time and space scales, ranging from atomic size ͑vacancy coalescence and initial void formation͒ to microns ͑plastic deformation and linkage of micron-sized voids͒. Consequently theoretical studies of spallation have used methods ranging from microscopic molecular-dynamics ͑MD͒ simulations, 7 to mesoscale micromechanical models and continuum descriptions.…”

“…The most widely used experimental methods are plate impact 1 and, more recently, high power pulsed laser shock generators. [2][3][4][5][6] Strain rates up to 10 8 sec Ϫ1 can be achieved with laser shocks, higher than those in plate impact experiments.…”

Mechanical Properties of Shock Treated Aluminium Alloy Al 2024-T4

“…The shock loading experiments are best suited for such studies, as, strain rates ranging from 10 3 /s -10 9 /s have been achieved in such experiments [1,2]. Further, the shock compression experiments designed properly can generate not only the high compressive stresses but also high tensile stresses in the materials [1][2][3] enabling to investigate material behaviour e.g. dynamic yield strength, spall fracture etc., in negative pressure regime also.…”