Iron zirconium multilayer films have been prepared by sputter deposition and studied using x-ray diffraction, high-resolution transmission electron microscopy and Nanoindenter techniques. The composition-modulation wavelength was varied between 0.8 and 92 nm. For modulation wavelengths greater than 4 nm the multilayers are crystalline with amorphous interfaces; for smaller wavelengths the samples are entirely amorphous. It was not possible to obtain layered structures with wavelengths smaller than 0.8 nm.
Both the hardness and the elastic modulus were measured as a function of composition-modulation wavelength by means of continuous indentation testing. The elastic modulus shows some variation with wavelength; the average value being 131 GPa. The hardness increases sharply when the modulation wavelength decreases below 4 nm. We attribute this increase to die crystalline to amorphous transition that occurs in these films at this wavelength.