The nucleation of super-dislocations from an intergranular crack tip in L12 intermetallic bi-crystals, and the intrinsic fracture behavior of L12 intermetallic alloys, were studied in this model material. The critical energy release rate for dislocation nucleation was obtained as a function of the inclination angles of the active slip planes. A micro-mechanical model was proposed to aid understanding of the intrinsic brittleness of L12 intermetallic alloys. This showed that converting the DO22 structure to the L12 structure did not guarantee ductile fracture behavior. This observation was consistent with published experimental results. It was suggested that attempts to develop ductile L12 alloys should involve alloying elements which could change the nature of the atomic bonding so that CSF-coupled dislocation dissociation was promoted.

Dislocation Nucleation and the Intrinsic Fracture Behavior of L12 Intermetallic Alloys J.S.Wang: Acta Materialia, 1998, 46[8], 2663-74