Deformation Mechanisms in Body-Centered Cubic Metals at High Pressures and Strain Rates
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Deformation mechanisms of single-crystal Ta oriented at four different crystal orientations: [001], [011], [$$\bar{1}11]$$, [$$\bar{1}23]$$ and shock-compressed at two different peak pressures: 50 GPa and 65 GPa using a gas gun flyer-plate impact method have been studied. The main objective of this investigation is to elucidate the shock-induced shear transformations: deformation twinning and the α (bcc) → ω (pseudo-hexagonal) transition which were observed to take place in shock-deformed polycrystalline Ta at 30 GPa when the formation of low-energy cellular dislocation structure and polygonization due to dynamic recovery becomes suppressed. Emphasis is placed on the effects of crystal orientation and strain rate on the shock-induced dynamic recovery and shear transformations. Novel mechanisms for the formation of cellular dislocation structure and polygonization based on the coupling reactions of the 1/2 < $$\bar{1}11$$ > coplanar dislocations in the { $$\bar{1}11$$ } slip planes are proposed to elucidate the competition between dynamic recovery and shear transformations.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- DOE Contract Number:
- AC52-07NA27344
- OSTI ID:
- 1481058
- Report Number(s):
- LLNL-TR-760731; 949304
- Country of Publication:
- United States
- Language:
- English
Similar Records
Transitions of Dislocation Glide to Twinning and Shear Transformation in Shock-Deformed Tantalum
Dynamic Dislocation Mechanisms For the Anomalous Slip in a Single-Crystal BCC Metal Oriented for "Single Slip"