Dislocation kinetics at high strain rates

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

“…It is well established that increasing the strain rate increases the CRSS by decreasing the time for a given dislocation to overcome a barrier to its motion. At extremely high strain rates, the glide of dislocations is further inhibited by mechanisms such as phonon drag [34,35].…”

Material dynamics under extreme conditions of pressure and strain rate

“…[9] Zerilli-Armstrong, [Zerilli, 1987;1990] Mechanical Threshold Stress (MTS), [Follansbee, 1988] thermal-activation-phonon-drag, [Hoge, 1977;Regazzoni, 1987] Steinberg-Lund, [Steinberg, 1989] Steinberg-Guinan, [Steinberg, 1980] and PrestonTonks-Wallace [Preston 2003] models are widely, for example. At the high strain rates relevant to the work described in this paper, thermal activation and dislocation glide along slip planes, resisted by phonon drag, are believed to be the dominant (rate determining) mechanisms underlying deformation.…”

“…At the high strain rates relevant to the work described in this paper, thermal activation and dislocation glide along slip planes, resisted by phonon drag, are believed to be the dominant (rate determining) mechanisms underlying deformation. [Kochs, 1975;Hoge, 1977;Regazzoni, 1987;Steinberg, 1989] These are illustrated schematically in Fig. 1a.…”

“…In the thermal activation regime, when a shear stress is applied, dislocations are assumed to be pinned against barriers, until a thermal fluctuation can kick them over the obstacle to glide to the next barrier. In this "jerky glide" regime, [Regazzoni, 1987] the strain rate is given by Orowan's equation, ˙ ! = " m bu , where u = " b /(t w + t g ) is the average dislocation velocity, λ b is the average distance between barriers, t w is the time spent waiting for a thermal assist, and t g is the time interval to freely glide to the next barrier.…”

“…5a. [Konningsberger, 1988;Lee, 1981;Rehr, 2000] When an atom absorbs an ionizing, high energy x-ray, an electron rises from a bound state into the continuum. The outgoing wave packet of the free electron, illustrated by the concentric solid circles in Fig.…”