Theory of environmental effects on transgranular fracture

Conference · Wed Jan 01 04:00:00 EST 1986

OSTI ID:5282542

Sieradzki, K

We discuss recent theoretical work on the transgranular stress-corrosion cracking of ductile metals. Computer simulations were used to study the behavior of cracks coated with thin solid films in the intrinsically ductile 2D triangular Lennard-Jones Solid. The key parameters studied were the elastic modulus mismatch and lattice parameter misfit between the film and substrate. It was found that elastically hard films could induce the nucleation of secondary brittle cracks in the normally ductile substrate. Films with a lattice parameter smaller than the substrate caused the crack to respond in a cleavage cracking mode, whereas films with a larger lattice parameter resulted in dislocation injection into the substrate. The concepts of film-induced cleavage and dynamic embrittlement are discussed. Molecular dynamic simulations were also used to study crack dynamics in the 2D triangular Johnson solid. Additionally we also present analytical calculations which explore the effects of thin film formation at crack tips on fracture. The parameters studied included elastic modulus mismatch, lattice parameter misfit and coherency. Suitable combinations of these parameters lead to film-induced micro-cleavage in ductile substrates. Finally crack dynamics are discussed and an estimation of film-induced micro-cleavage distances is presented.

• Research Organization: Brookhaven National Lab., Upton, NY (USA)
• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5282542
• Report Number(s): BNL-38616; CONF-8606168-2; ON: DE86016165
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
CHEMICAL REACTIONS
COMPUTERIZED SIMULATION
CORROSION
CRACK PROPAGATION
CRACKS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
DUCTILITY
ELEMENTS
EMBRITTLEMENT
FAILURES
FILMS
FRACTURES
LINE DEFECTS
MECHANICAL PROPERTIES
METALS
SIMULATION
STRESS CORROSION
TENSILE PROPERTIES
THIN FILMS