TiN/Si3N4界面结构对Ti-Si-N纳米晶复合膜力学性能的影响

采用多层膜模拟的方法研究了Ti-Si-N纳米晶复合膜中Si3N4界面相的存在方式，以探讨纳米晶复合膜的超硬机制。研究结果表明：Si3N4层厚对TiN／Si3N4多层膜的微结构和力学性能有重要影响。当Si3N4层厚小于0．7nm时，因TiN晶体的“模板效应”，原为非晶态的Si3N4晶化，并反过来促进TiN的晶体生长，从而使多层膜呈现TiN层和Si3N4层择优取向的共格外延生长。相应地，多层膜产生硬度和弹性模量升高的超硬效应，最高硬度和弹性模量分别为34．0GPa和352GPa．当层厚大于1．3nm后，Si3N4呈现非晶态，多层膜中TiN晶体的生长受到Si3N4非晶层的阻碍而形成纳米晶，薄膜的硬度和弹性模量亦随之下降。由此可得，Ti-Si-N纳米晶复合膜的强化与多层膜中2层不同模量调制层共格外延生长产生的超硬效应相同。

The Influence of TiN/Si3N4 Interfacial Structure on the Mechanical Properties of Ti-Si-N Nanocomposite Film

The structure of interface phase of Si3N4 in Ti-Si-N nanocomposite films were studied by a simulation based on TiN/Si3N4 nanomultilayers, in order to disclose the superhard mechanism of composite films. The results show that the Si3N4 layer thickness has great influence on the microstructure and mechanical properties of TiN/Si3N4 nanomultilayers. Because of the template effect of TiN, Si3N4 can form crystalline structure when Si3N4 layer thickness is less than 0.7 nm. Then the crystals can promote the growth of TiN, which results in that the film forms epitaxial coherent superlattice. Correspondingly, the hardness and elastic modulus of the films are obviously enhanced and reach the maximum values of 34. 0 and 352 GPa, respectively. When its thickness is larger than 1.3 nm, Si3N4 exists as amorphous structure and prevents TiN from epitaxial coherent growth, which decreases the hardness and elastic modulus of the multilayers. In conclusion, Ti-Si-N composite films have the same strengthening mechanism as the superhard nanomultilayers consisting of two modulation layers with different modulus.