Dislocation multiplication in f. c. c. metals at presence of high shear stress
- Ben-Gurion Univ. of the Negev, Beer-Sheva (Israel). Dept. of Mechanical Engineering
A new model of shock-induced stress relaxation based on multiplication and motion of partial dislocations bounding the stacking fault is suggested. Shock-generated high shear stress leads to stretching of lateral branches of a bowed out dislocation segment (half-loop) followed by collapse of those branches. The result of the collapse is the forming of the fresh'' partial dislocation loop bounding the stacking fault area and initial'' dislocation half-loop, both being capable of the next multiplication act. After every collapse time interval [Delta]T the process leads to the doubling of both the dislocation concentration and stacking faults total area. The energy dissipation rate behind the shock front increases exponentially dW/dt [approximately] 2[sup t/[Delta]T], but is should be limited as soon as the cross-slip of the fresh'' loops will be impeded and the loops doubling will be stopped. An explanation of twinning and shear bands formation in shocked material is proposed.
- OSTI ID:
- 6550090
- Journal Information:
- Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 43:1; ISSN 0956-7151; ISSN AMATEB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
ELEMENTS
ENERGY LOSSES
IMPACT SHOCK
LINE DEFECTS
LOSSES
MATHEMATICAL MODELS
METALS
MICROSTRUCTURE
RELAXATION
STRESS RELAXATION
TWINNING