HIGH-RESOLUTION STRUCTURE IMAGING OF STACKING SEQUENCES IN Y2FE17CX(0.6X1.6) MAGNETIC MATERIAL

Abstract High-resolution electron microscopy has been used to investigate planar crystal defects in magnetic materials of the type Y2Fe17C x (x0·6), which have the rhombohedral Th2Zn17 type of structure. The basal plane stacking sequences are imaged in the [100] orientation. Edge-on and inclined coherent twin boundaries are observed, the latter giving rise to a characteristic coincidence site pattern. The high-resolution images further reveal a high density of conservative and non-conservative antiphase boundaries, which can mutually combine into an antiphase boundary cross-link. Non-conservative antiphase boundaries are also seen to make cross-links between successive twin boundaries. In local areas, a periodic antiphase boundary structure with Y3Fe29C x , stoichiometry is observed. Y2Fe17C x compounds resulting from an annealing treatment at low temperature exhibit an order-disorder phenomenon, based upon the rhombohedral structure. High-resolution structure imaging allows us to confirm the microdomain...