Dislocation enhancement and inhibition induced by films on crack surfaces
Computer simulations were used to study the propagation of cracks coated with thin solid films in a 2D triangular Lennard-Jones solid. The key parameter investigated was the mismatch in the interatomic distances of the film and the substrate (the eleastic moduli were kept the same). The major result is that ''Large Film Atoms,'' i.e. interatomic distance in the film larger than in the substrate, promote dislocation generation at the film-substrate interface while ''Small Film Atoms'' inhibit dislocation formation and promote brittle fracture in an otherwise ductile material. The critical applied load to cause fracture decreased significantly with increasing film thickness. These results are in qualitative agreement with some currently available experimental data. A model was developed which explains the simulation results in terms of the residual stresses resulting from the ''atomic size'' mismatch of film and substrate. The fact that cracks propagated brittly in the substrate after the film was ruptured is explained in terms of a model for dynamic embrittlement.
- Research Organization:
- Queens College of CUNY, Flushing, NY
- OSTI ID:
- 6141083
- Journal Information:
- Acta Metall.; (United States), Vol. 31:8
- Country of Publication:
- United States
- Language:
- English
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Enhancement of dislocation generation induced by films on crack surfaces
Computer modeling of cracks
Related Subjects
ALLOYS
ATOM TRANSPORT
CRACK PROPAGATION
DISLOCATIONS
FRACTURE MECHANICS
RESIDUAL STRESSES
METALS
BRITTLENESS
COATINGS
COMPUTERIZED SIMULATION
CRACKS
DYNAMICS
EMBRITTLEMENT
FILMS
INTERFACES
PHYSICAL METALLURGY
SUBSTRATES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
ELEMENTS
LINE DEFECTS
MECHANICAL PROPERTIES
MECHANICS
METALLURGY
NEUTRAL-PARTICLE TRANSPORT
RADIATION TRANSPORT
SIMULATION
STRESSES
360103* - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies