Fe-16Al alloy and Cr18-Ni8 austenitic stainless steel were diffusion bonded in a vacuum of 10(-4) Pa. Microstructure characteristics at the bonded Fe-16Al/Cr18-Ni8 interface were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD) technologies. The results indicated that FeAl, Fe3Al, Ni3Al and alpha-Fe (Al) solid solutions were produced at the bonded Fe-16Al/Cr18-Ni8 interface after diffusion bonding. These phases may accelerate the diffusion and even the formation of the bonded Fe-16Al/Cr18-Ni8 interface. The growth of the interface obeyed the parabolic law and its thickness (X) was expressed by X-2 = 7.0 X 10(-4)exp(-82900/RT)(t-t(0)) with temperature (T) and time (t).