A T.E.M INVESTIGATION OF THE MECHANISM OF EARLY STAGE ORDERING IN THE INTERMETTALIC COMPOUND PT2FECU

Abstract: The microstructural features of the early stage of ordering of the intermetallic compound Pt2FeCu have been examined using optical and transmission electron microscopy in conjunction with X-ray diffraction technique. It was found that the compound has similar morphological alteration to that of FePt in which the ordering cannot be suppressed by rapid quenching. The early stage of ordering transformation was initiated at temperatures above the critical value of 1178 oC, by a homogeneous nucleation of the intermediate short range ordered particles and ultra rapid directional-induced heterogeneous growth (burst type). As the result of these combined mechanisms, twin –related ordered domains have been formed which in turn minimize the strains produced by ordering reaction in polycrystalline material. The individual grain was divided up by different sizes of twin-related ordered domain bonded with {101} habit planes.