A TEM STUDY OF [110](001) SLIP IN CREPT POLYCRYSTALLINE NI3AL

The dislocation microstructure of a polycrystalline Ni3Al specimen cre pt for 196 h al 580 degrees C (below T-p) has been observed using TEM. The vast majority of the dislocations consist of rectangular [110] di slocation loops lying approximately on cube planes. The sides of the r ectangles consist of pure edge and pure screw dislocations. The edge s ides are stepped and one of them lies above the other relative to the overall cube habit plane. There are also figure-of-eight loops and sin gle-turn helices. A double cross-slip mechanism based on the cube plan es explains the observations.