Dynamic yield and tensile strength of aluminum single crystals at temperatures up to the melting point

Abstract

This article presents experimental results of the dynamic yield strength and dynamic tensile strength (“spall strength”) of aluminum single crystals at shock-wave loading as a function of temperature. The load duration was ∼40 and ∼200 ns. The temperature varied from 20 to 650 °C which is only by 10 °C below the melting temperature. A linear growth of the dynamic yield strength by more than a factor of 4 was observed within this temperature range. This is attributed to the phonon drag effect on the dislocation motion. High dynamic tensile strength was maintained over the whole temperature range, including the conditions at which melting should start in a material under tension. This could be an indication of the existence of superheated states in solid crystals.

The shock and spall response of three industrially important hexagonal close-packed metals: magnesium, titanium and zirconium

“…However, it is not clear that this process would occur quickly enough to result in the observed strengthening during shock loading. Similar behaviour has been seen in heated single crystals of aluminium where the cause of the strength increase was attributed to phonon drag on dislocations [50]. It has also been seen in stainless steels [51].…”

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.…”

The resistance to deformation and facture of magnesium ma2-1 under shock-wave loading at 293 k and 823 k of the temperature

“…Figure 6 presents an example of the free surface velocity history measured at elevated temperature in comparison with the room temperature data at the same impact conditions. Unlike to aluminum [9][10][11] the alloy does not exhibit anomalous increase of the HEL with heating. Accounting for decreasing elastic moduli with growth of the temperature, it follows from presented data that the dynamic yield stress decreases with heating.…”