Micromechanisms of brittle fracture: Acoustic emissions and electron channeling analyses

Technical Report · Fri Jun 01 04:00:00 EDT 1990

DOI:https://doi.org/10.2172/6494088· OSTI ID:6494088

Gerberich, W W

The objectives of this work are to: (i) Evaluate the initial stages of cleavage nucleation in single and polycrystalline samples; (ii) Determine the controlling event(s) which lead(s) to unstable cleavage (is it an unstable cluster'' of microcracks or a crack-tip opening displacement criterion for an array of ligaments surrounding these microcracks ); (iii) Determine how the process zone, which depends upon microstructure and processing history, affects the controlling event(s); (iv) Use selected area channeling patterns (SACP's) to assist in an independent measure of the cleavage fracture stress of grains cleaved at or just outside the elastic-plastic boundary; also, use it to evaluate static and dynamic strain distributions; and (v) Evaluate the effects of dislocation shielding and overload using combined methods of computational mechanics with discretized dislocation arrays and direct observations of dislocations using channeling, etch pit and birefringence methods. Accomplishments are discussed. 15 refs., 3 figs.

• Research Organization: Minnesota Univ., Minneapolis, MN (USA). Dept. of Chemical Engineering and Materials Science
• Sponsoring Organization: DOE/ER
• DOE Contract Number: FG02-84ER45141
• OSTI ID: 6494088
• Report Number(s): DOE/ER/45141-T5; ON: DE91000987
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360603 -- Materials-- Properties
CHANNELING
CRYSTALS
ELECTRON CHANNELING
EMBRITTLEMENT
EQUATIONS
FRACTURE MECHANICS
HYDROGEN EMBRITTLEMENT
MECHANICS
MONOCRYSTALS
POLYCRYSTALS