O-lattice modeling of ledged, partially coherent b.c.c.:h.c.p. boundaries

Abstract

The structure of ledged, partially coherent b.c.c.:h.c.p. ( β: ζ) interfaces has been modeled by extending the Bollmann O-lattice theory to permit the matching of all atom positions in the two crystal structures and the matching between relaxed atom positions, each of which creates a set of additional O-points. Misfit-compensating ledges and structural ledges are predicted when interphase boundaries made up of parallel steps and terraces intersect additional O-points. Misfit-compensating ledges with Burgers ( 1 100) ζ(2 11) β and Pitsch-Schrader (2 110) ζ( 100) β terraces have Burgers vectors and interledge spacings both one half those associated with misfit dislocations on the corresponding flat interfaces. Biatomic structural ledges with Burgers (1 100) ζ(2 11) β and Potter (1 101) ζ(10 1) β terraces are shown to have Burgers vectors and interledge spacings both one sixth of their misfit dislocation counterparts.