Fracture toughness from atomistic simulations: Brittleness induced by emission of sessile dislocations

Journal Article · Tue Aug 04 04:00:00 EDT 1998 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(98)00193-6· OSTI ID:651148

Farkas, D ^[1]

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1. Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Materials Science and Engineering

Using atomistic simulations of crack response for intermetallic materials the author shows that when the emitted dislocations are sessile and stay in the immediate vicinity of the crack tip the emitted dislocations can actually lead to brittle failure. She present the results of an atomistic simulation study of the simultaneous dislocation emission and crack propagation process in this class of materials. She used a molecular statics technique with embedded atom (EAM) potentials developed for NiAl. The crystal structure of NiAl is the CsCl type (B2) with a lattice parameter of 0.287 nm, which is reproduced by the potential together with the cohesive energy and elastic constants. The compound stays ordered up to the melting point, indicating a strong tendency towards chemical ordering with a relatively high energy of the antiphase boundary (APB). As a result of this relatively large energy the dislocations of 1/2<111> type Burgers vectors imply a high energy and the deformation process occurs via the larger <100> type dislocations.

• OSTI ID: 651148
• Report Number(s): CONF-980202--
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 4-5 Vol. 39; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CRACK PROPAGATION
CRACKS
DISLOCATIONS
FRACTURE PROPERTIES
INTERMETALLIC COMPOUNDS
MICROSTRUCTURE
NICKEL ALLOYS
SIMULATION