ATOMIC-STRUCTURE OF DISLOCATIONS AT THE I NTERSECTION OF STACKING-FAULTS IN AN (NI,CO) F.C.C. CRYSTAL

A (Ni, Co)-based two-phase superalloy has been plastically deformed at room temperature, producing various dislocation and stacking-fault co nfigurations in the f.c.c. matrix. The structures of some dislocation cores were observed at atomic scale using high-resolution electron mic roscopy, namely a (b = 1/3[110]) stair-rod and (b = 1/6[112]) Shockley partials at the intersections of crossing intrinsic or extrinsic faul ts. The displacement fields of the surrounding atomic columns are foun d to be in good agreement with the fields calculated using anisotropic elasticity theory, except quite close to the cores of the dislocation s.