Microstructural development and stability in cast Ni-30 at % Al-21 at % Cr-4 at % Ti, Ni-28 at % Al-18 at % Cr-6 at % Ti and Ni-26 at % Al-19 at % Cr-8 at % Ti alloys are examined in this paper. The paper considers the extent to which microstructural control and stability is improved in these alloys, when compared with earlier work by the authors on similar materials with lower aluminum (25 or 26 at %) and higher titanium (11 to 15 at %) contents. The paper discusses detailed transmission electron microscopy investigations of both as-cast and aged (140 h at 850 and 1100 degrees C) samples. Attention is focussed on the transformation of L2(1) type beta' (nominally Ni2AlTi) dendrites. In particular, the influence of the formation of intradendritic L1(2) type gamma' (nominally Ni-3(Al,Ti)) on the stability of the beta'-phase is examined. Morphological changes and phase transformations within a beta'-alpha-Cr eutectic are discussed. Various modes of second-phase precipitation are considered. The microstructures of selected samples are correlated with mechanical properties determined by tensile testing and fractography.