The mechanical behaviour of dual-phase microstructures, consisting of elongated primary NiAl grains aligned with an intergranular NiAl/X eutectic phase, produced by extrusion of cast NiAl-X (where X=Cr and W) alloys, has been examined. Chromium, added to create a dual-phase NiAl-based aligned microstructure, resulted in large increases in the yield strength, but only marginal improvement in the toughness. In contrast, tungsten alloying leads to ductility or toughness increases with no significant strengthening. The constitutional hardening rate due to deviations from stoichiometry in Ni rich NiAl was estimated to be about 66 MPa (Ni-1 at%).