Tri-aluminide alloys having the cubic L12 structure were investigated. The alloys fractured in a brittle manner (fracture toughness, 2 to 3MPam½), predominantly by transgranular cleavage. The room-temperature hardness and yield strength values (100 to 200DPH, 100 to 270MPa) of all of the alloys were low (comparable to ductile L12 alloys such as Ni3Al), indicating significant dislocation activity. Transmission electron microscopy identified several antiphase boundary-coupled dislocations with b = a/2[110], gliding on the {111} planes in Al-23Ti-6Fe-5V. The separation between the super-partials in was 4nm, giving an antiphase boundary energy of 274mJ/m2.

Brittle Cleavage of L12 Trialuminides. E.P.George, J.A.Horton, W.D.Porter, J.H.Schneibel: Journal of Materials Research, 1990, 5[8], 1639-48