BSTRACTWe use analytical aberration-corrected high-resolution scanning transmission electron microscopy to image the atomic structure of the layered ternary transition metal (M) borides

Cr

2

AlB

2

Fe

2

AlB

2

and MoAlB. In these ternaries

MB layers and Al single or double atomic layers are interleaved. The atomic positions of the M elements and Al are clearly resolved by Z-contrast images. The following structural defects are also found and described herein: a 90° twist boundary along [010

]

in Cr

2

AlB

2

a tilt boundary in Fe

2

AlB

2

and Mo

2

AlB

2

-like stacking faults in MoAlB

where some of the MB-based structures are intercalated by one (instead of two) Al layer(s).