CHARACTERIZATION OF DOMAIN BOUNDARIES IN NI4MO BY CONVERGENT-BEAM ELECTRON-DIFFRACTION

The alloy Ni-20 at.% Mo (Ni4Mo) is disordered (alpha) above 868 degree s C and ordered (beta) below this temperature. Upon the formation of b eta from the alpha, a variety of interfaces between the ordered domain s is formed. Characterizing the domain interfaces by using conventiona l selected-area diffraction can be difficult since, in some orientatio ns, superlattice diffraction spots are identical with those of the alp ha-phase. However, convergent beam electron diffraction can be used to examine the higher-order Laue zone patterns, in which superlattice sp ots can be revealed. Also this technique produces the diffraction patt ern from a very small analysis area. We have used this method to ident ify some of the characteristics of domain boundaries in the ordered Ni 4Mo alloy.