Fe/Ti纳米多层薄膜退火初期的扩散行为

Diffusion in Initial Stage of Thermal Annealing of Fe/Ti Nanometer-Scale Multilayers

采用双室高真空磁控溅射装置在溅射功率60 W和工作气压0.5 Pa下直流磁控溅射沉积了调制比为1,设计调制周期18.0 nm的Fe/Ti纳米多层薄膜.利用横截面透射电镜(XTEM)、差示扫描量热分析仪(DSC)及小角和广角X射线衍射(SA/WAXRD)分析退火初期的扩散行为.实测调制周期16.2nm,原始沉积Fe/Ti纳米多层薄膜由交替生长的纳米多晶α-Fe和α-Ti组成,调制界面清晰.Fe/Ti纳米多层薄膜热失稳过程包括亚层间的扩散、金属间化合物FeTi形成和长大3个阶段.退火温度为473 K时,保持与原始沉积相同的成分调制结构;退火温度升高到523 K,Fe与Ti亚层间发生互扩散,成分调制结构破坏,但相变未发生;达到最高退火温度623 K,过饱和固溶体α-Fe(Ti)和金属间化合物FeTi形成.

Fe/Ti nanometer-scale multilayers of nominal bilayer thickness of 18.0 nm with alternating Fe and Ti sublayers thickness ratio of 1 ： 1 were deposited by direct current magnetron sputtering using a sputtering target supply power of 60 W under working pressure of 0.5 Pa. The initial stage of thermal annealing of the Fe/Ti nanomete-scale multilayers was investigated by cross-sectional transmission electron microscopy （XTEM）, differential scanning calorimetry （DSC） and small and wide angle X-ray diffraction （SA/WAXRD）. There are three stages of thermal annealing： the diffusion between the alternating Fe and Ti sublayers, the formation and growth of the intermetallic FeTi. The as-deposited Fe/Ti multilayers with a modulation wavelength of 16.2 nm are composed of nanocrystalline α -Fe and α -Ti with a clear interface between the sublayers. With annealing at 473 K, the Fe/Ti nanometer-scale multilayers remain the as-deposited modulation structure. At 523 K, the modulation structure almost disappears due to the interdiffusion between the Fe and Ti sublayers and no intermetallic FeTi is formed. At 623 K, the supersaturated α -Fe（Ti） solid solution and intermetallic FeTi are detected in the multilayers.