Ion beam modifications to thin-film, polycrystalline Ni-Al alloys have been investigated using high resolution [0.1 eV full width at half maximum (FWHM)] transmission electron energy loss spectroscopy (EELS). The ion-induced modification of Ni3Al, NiAl, Ni2Al3, and NiAl3, as measured by EELS, is compared to concurrent electron microscope diffraction analyses. The EELS core level spectra corroborate the NiAl3 to amorphous phase transition observed by diffraction, while the EELS valence spectra provide a signature for the Ni2Al 3 to NiAl phase transformation. These results reflect the changes in the electronic states caused by changes in the crystal structure. In addition, perturbations to the electronic states are measured even when no change appears in the diffraction pattern (irradiated NiAl). Thus, high-resolution EELS is shown to be a sensitive analytical technique for studying ion irradiated materials.