Si3N4的晶体化和ZrN/Si3N4纳米多层膜的超硬效应

研究了Si₃N₄层在ZrN/Si₃N₄纳米多层膜中的晶化现象及其对多层膜微结构与力学性能的影响. 一系列不同Si₃N₄层厚度的ZrN/Si₃N₄纳米多层膜通过反应磁控溅射法制备. 利用X射线衍射仪、高分辨透射电子显微镜和微力学探针表征了多层膜的微结构和力学性能. 结果表明，由于受到ZrN调制层晶体结构的模板作用，溅射条件下以非晶态存在的Si₃N₄层在其厚度小于0.9 nm时被强制晶化为NaCl结构的赝晶体，ZrN/Si₃N₄纳米多层膜形成共格外延生长的柱状晶，并相应地产生硬度升高的超硬效应. Si₃N₄随层厚的进一步增加又转变为非晶态，多层膜的共格生长结构因而受到破坏，其硬度也随之降低.

Crystallization of Si3N4 and superhardness effect of ZrN/Si3N4 nano-multilayers

The crystallization behavior of Si₃N₄ modulation layers in the multilayers and its influences on the microstructure and mechanical properties of ZrN/Si₃N₄ multilayers were studied. ZrN/Si₃N₄ multilayers with different Si₃N₄ thickness were synthesized by reactive magnetic sputtering. The microstructure of the multilayers was characterized with X-ray diffraction and high-resolution transmission electron microscopy, and a nanoindentor was introduced to measure their mechanical properties. The results show that when the thickness is less than 0.9 nm, Si₃N₄, normally amorphous in the deposited state, could form a NaCl-type pseudocrystal structure due to the template effect of ZrN crystal layer. Crystallized Si₃N₄ layers and ZrN template layers grow epitaxialy into columnar crystals. Correspondingly, the hardness of the films was enhanced, showing a superhardness effect. Further increasing Si₃N₄ layer thickness, the coherent interfaces of the multilayers were damaged and Si₃N₄ layers become amorphous, accompanied by the decline in the hardness of the films.