Atomic-scale microstructures of Zr2Al3C4 and Zr3Al3C5 ceramics

The microstructures of bulk Zr2Al3C4 and Zr3Al3C5 ceramics have been investigated using transmission electron microscopy and scanning transmission electron microscopy. These two carbides were determined to have a point group 6/mmm and a space group P63/mmc using selected-area electron diffraction and convergent beam electron diffraction. The atomic-scale microstructures of Zr2Al3C4 and Zr3Al3C5 were investigated through high-resolution imaging and Z-contrast imaging. Furthermore, intergrowth between Zr2Al3C4 and Zr3Al3C5 was identified. Stacking faults in Zr3Al3C5 were found to result from the insertion of an additional Zr–C layer. Cubic ZrC was occasionally identified to be incorporated in elongated Zr3Al3C5 grains. In addition, Al may induce a twinned ZrC structure and lead to the formation of ternary zirconium aluminum carbides.