It was noted that complex faults were present on the {100} planes of 40at%Al alloys which contained 0.7at%C and 0.5at%B, but were not present in samples which contained 0.6at%C. The fault had a displacement vector of ½<001> which lay in the plane of the fault. There was also a layer of Al missing from the fault, and perhaps B segregation. Six variants of the fault were possible. The presence and form of the fault were thought to depend upon the heat-treatment temperature, and cooling-rate; via their effect upon the creation and migration of B-vacancy complexes. The width of the complex fault was suggested to be a function of the heat-treatment temperature. In material which had been quenched and annealed, or air-cooled from 1000 or 800C, these faults seemed to be bounded by partial dislocations which had a Burgers vector of ½<001>. When these faults were imaged edge-on, they sometimes exhibited a zig-zag appearance. This was assumed to indicate the occurrence of faceting on the cube planes. Thermal antiphase boundaries were also observed after some heat treatments, and were suggested to be a result of recrystallization of the extruded structure.

Complex Faults in a B2 Iron Aluminide Alloy. L.Pang, K.S.Kumar: Acta Materialia, 2001, 49[12], 2215–26