Aberration-corrected electron microscopy (ACEM), combined with x-ray energy dispersive spectroscopy (XEDS), has been applied to studies of phase transformations and microstructural evolution in metallic alloys. In this talk, a report will be given of research into these phenomena in titanium alloys and compositionally complex alloys (CCA). In the case of the former alloys, the STEM-HAADF technique has been used to image transverse and longitudinal phonons, and the role of these lattice instabilities in heterogeneous nucleation has been identified. In the case of the latter alloys, accurate descriptions of their complex microstructures have been achieved using electron tomography coupled with XEDS. Also, a combination of ACEM and XEDS has been used in an attempt to determine the degree of order in B2 compounds that are a part of the microstructure in a number of CCAs. Limitations of this technique will be outlined by reference to the case of a standard sample (NiAl).