Figure 1

Transmission electron microscopy micrographs of four carbides: M₂₃C₆, M₇C₃, M₃C, and M₂C. Morphology (a,c) and selected area electron diffraction (SAED) (b,d) of Fe_19.51Cr_3.49C₆, M₇C₃, M₃C and M₂C carbides during tempering at 823 K for 3600 s in the presence of a 12 T magnetic field. The measured aspect ratio for ellipsoid M₂₃C₆ is almost independent of whether the external field is applied or not²⁵. For M₂₃C₆ in Fig. 1b, the spots that satisfy the condition that h, k, and l are all odd or all even are identified by means of SAED patterns. The characteristic faulted structure of M₇C₃ particles makes them easy to distinguish from particles of other carbides³⁴. In Fig. 1d, the same diffraction ring within experimental errors corresponds to different crystal planes due to the similar d-spacing for orthorhombic M₃C and M₂C.