纳米复合超硬薄膜中与界面有关的弛豫现象

RELAXATION PROCESS ASSOCIATED WITH INTERFACES IN SUPERHARD NANOCOMPOSITE FILMS

利用内耗技术研究了TiSiN系列纳米复合超硬薄膜的结构弛豫和硬化机理。当共振频率大约在100Hz时在230～280℃范围内观察到一个弛豫型的内耗峰。计算出激活能为0．7～1．0eV，弛豫时间指数前因子为10^-10～10^-12秒。对比一系列样品。发现硬度越高内耗峰越低，在硬度高于50GPa的薄膜中没有内耗峰。内耗峰随退火温度升高而不断降低，直至600～750℃退火时消失，并且杨氏模量开始增加，这跟样品退火后硬度增长是一致的。结果表明内耗峰来源于样品中界面的弛豫过程。

The internal friction technique is exploited to study the structural relaxation and hardening mechanism of TiSiN superhard nanocomposite films. A relaxation peak was observed around 230 ～ 280℃ when f = 100 Hz. The activation energy and the preexponential factor of the relaxation time were deduced as 0. 7～1.0 eV and 10^-10～10^-12 s,respectively. It is found by comparing the results of a series of samples that the higher the hardness of the films is, the lower the height of the internal friction peak is. There was no peak in the films with hardness greater than 50 GPa. This peak decreases in height with increasing annealing temperature, and disappears after annealed at 600～750 ℃. At the same time, the Young＇s modulus increases, in accordance with the increase of hardness with annealing temperature. The results show that this internal friction peak is originated from the relaxation process within the interfaces.