It was recalled that plane-wave shock deformation produced deformation twins or twin-faults in almost all metals and alloys. In face-centered cubic metals and alloys, twinning depended upon the stacking-fault energy and a critical twinning pressure; which increased with increasing stacking-fault energy. In impact cratering, where the shock wave was spherical and a prominent shear stress was involved, metals and alloys which had a high stacking-fault energy formed micro-bands which coincided with {111} plane traces. Meanwhile, low stacking-fault energy metals and alloys either formed mixtures of twins and micro-bands, or micro-twins. The oblique shock-loading of Cu also produced mixtures of twins and micro-bands. Both micro-twins and micro-bands increased in volume fraction with increasing grain size. Body-centered cubic Fe was observed to twin during shock loading or impact cratering. Various other examples of extreme deformation, and flow at high strain-rates, involved various regimes of shear-banding and dynamic recrystallization as mechanisms of solid-state flow. Deformation twins and micro-bands were also often their precursors.

Observations of Common Microstructural Issues Associated with Dynamic Deformation Phenomena - Twins, Microbands, Grain Size Effects, Shear Bands, and Dynamic Recrystallization. L.E.Murr, E.V.Esquivel: Journal of Materials Science, 2004, 39[4], 1153-68