Structural Characterization And Evolution During Thermal Annealing For Fe/Ti Nanometer-scale Multilayers

The Fe/Ti nanometer-scale multilayers of modulation wavelength of 9.5-116.4 nm with thickness ratio of 1:1 and different preferred orientation were deposited by direct current magnetron sputtering in the duplex chamber magnetron sputtering apparatus using a sputtering target supply power of 60-80 W under working pressure of 0.5-0.9 Pa. Structural characterization and evolution of Fe/Ti nanometer-scale multilayers during thermal annealing at 473-873 K for 1 h were investigated by using small/wide angle x-ray diffraction, Rutherford backscattering spectrometry, cross-sectional transmission electron microscopy and differential scanning calorimetry. The as-deposited Fe/Ti nanometer-scale multilayers were composed of nanocrystalline α-Fe and α-Ti with a certain preferred orientation along the direction perpendicular to the surface. For the Fe/Ti nanometer-scale multilayers with preferred orientation of α-Fe (110) and α-Ti (002), the grain size in the Fe and Ti sublayers became larger with the modulation wavelength increasing from 9.5 nm to 116.4 nm. With a certain bilayer thickness of 16.0 nm, the grain size increased from 10 nm to 40 nm as the preferred orientation of α-Ti phase changed from (002) to (100). The Fe/Ti nanometer-scale multilayers underwent three stages of the interdiffusion between sublayers, and the formations of intermetallic FeTi and Fe₂Ti during thermal annealing, corresponding to the active energy 0.95 eV, 1.41 eV and 2.01 eV, respectively. The modulation wavelength and preferred orientation of sublayers have an effect on the structural evolution in Fe/Ti nanometer-scale multilayers during thermal annealing. The intermetallics fomed at higher annealing...