SMALL-ANGLE GRAIN-BOUNDARIES IN HOT-DEFORMED TAU(2)-AL13CO4

Transmission electron microscope (TEM) was used to study small-angle g rain boundaries in monoclinic tau(2)-Al13Co4 phase (Pm, a = 3.984 nm. b = 0.8148 nm: c = 3.223 nm and beta = 107.97 degrees) as introduced b y deformation at high temperatures. According to the character of the dislocations of which the small-angle grain boundaries consist, three types of small-angle grain boundaries have been observed: a zigzag bou ndary consisting of parallel screw dislocations; a tilt boundary consi sting of an edge-dislocation wall; a small-angle grain boundary consis ting of a dislocation network.