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

Plane-wave shock deformation has been shown to produce deformation twins or twin-faults in essentially all metal and alloys. In FCC metals and alloys twinning depends upon stacking-fault free energy (SFE) and a critical twinning pressure; which increases with increasing SFE. For impact cratering whe...

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Bibliographic Details
Published in:Journal of materials science 2004-02, Vol.39 (4), p.1153-1168
Main Authors: Murr, L. E, Esquivel, E. V
Format: Article
Language:English
Subjects:
Aluminum
Copper
Craters
deformation
Deformation effects
Deformation mechanisms
Dynamic recrystallization
Edge dislocations
energy
FCC metals
Free energy
Geological faults
Grain size
iron
Materials science
Metallography
Metals
Microtwins
molybdenum
Nickel
Shaped charges
Shear bands
Shock loading
Shock waves
Size effects
Spherical waves
stainless steel
Stainless steels
Tantalum
Transmission electron microscopy
Tungsten
Twinning
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Summary:Plane-wave shock deformation has been shown to produce deformation twins or twin-faults in essentially all metal and alloys. In FCC metals and alloys twinning depends upon stacking-fault free energy (SFE) and a critical twinning pressure; which increases with increasing SFE. For impact cratering where the shock wave is spherical and a prominent deviatoric (shear) stress is involved, metals and alloys with high SFE form microbands coincident with {111} plane traces while low SFE metals and alloys either form mixtures of twins and microbands or microtwins. Oblique shock loading of copper also produces mixtures of twins and microbands. Both microtwins and microbands increase in volume fraction with increasing grain size. BCC iron is observed to twin in both shock loading and as a result of impact cratering. Impact craters, shaped charges, and other examples of extreme deformation and flow at high strain rates exhibit various regimes of shear bands and dynamic recrystallization as a mechanism for solid-state flow. Deformation twins and microbands are also often precursors to this process as well. Examples of these phenomena in FCC materials such as Al, Ni, Cu, stainless steel and brass, and BCC materials such as Fe, W, Mo, W-Ta, and Ta are presented; with emphasis on optical metallography and transmission electron microscopy.
ISSN:0022-2461
1573-4803
DOI:10.1023/B:JMSC.0000013870.09241.c0