Observations of common microstructural issues associated with dynamic deformation phenomena: Twins, microbands, grain size effects, shear bands, and dynamic recrystallization

摘要: Plane-wave shock deformation has been shown to produce twins or twin-faults in essentially all metal and alloys. In FCC metals alloys twinning depends upon stacking-fault free energy (SFE) a critical pressure; which increases with increasing SFE. For impact cratering where the wave is spherical prominent deviatoric (shear) stress involved, high SFE form microbands coincident {111} plane traces while low either mixtures of microtwins. Oblique loading copper also produces microbands. Both microtwins increase volume fraction grain size. BCC iron observed twin both as result cratering. Impact craters, shaped charges, other examples extreme flow at strain rates exhibit various regimes shear bands dynamic recrystallization mechanism for solid-state flow. Deformation are often precursors this process well. Examples these phenomena materials such Al, Ni, Cu, stainless steel brass, Fe, W, Mo, W-Ta, Ta presented; emphasis on optical metallography transmission electron microscopy.